This list contains acronyms, initialisms, and pseudo-blends that begin with the letter S.

For the purposes of this list:

• acronym = an abbreviation pronounced as if it were a word, e.g., SARS = severe acute respiratory syndrome, pronounced to rhyme with cars
• initialism = an abbreviation pronounced wholly or partly using the names of its constituent letters, e.g., CD = compact disc, pronounced cee dee
• pseudo-blend = an abbreviation whose extra or omitted letters mean that it cannot stand as a true acronym, initialism, or portmanteau (a word formed by combining two or more words).

(a) = acronym, e.g.: SARS – (a) severe acute respiratory syndrome

(i) = initialism, e.g.: CD – (i) compact disc

(p) = pseudo-blend, e.g.: UNIFEM – (p) United Nations Development Fund for Women

(s) = symbol (none of the above, representing and pronounced as something else; for example: MHz – megahertz)

Some terms are spoken as either acronym or initialism, e.g., VoIP, pronounced both as voyp and V-O-I-P.

(Main list of acronyms)

• S
  • (s) Siemens
  • South
  • Sulphur/Sulfur

• S followed by a number is used to denote various German and Austrian S-train lines.
• S4C – (i) Sianel Pedwar Cymru (Welsh, "Channel Four Wales")
• S3 - (i) Alternative to SSS (e.g. Amazon S3)

• sa – (s) Sanskrit language (ISO 639-1 code)
• SA
  • (i) Salvation Army
  • (s) Sand (METAR Code)
  • Saudi Arabia (ISO 3166 and FIPS 10-4 country's code digram)
  • (i) Sexaholics Anonymous
  • Sexual assault
  • (i) sine anno (Latin, "without year")
  • Single Adult, a designation in the LDS Church for unmarried individuals 18 and older
  • Situational awareness
  • South Africa
  • (i/s) South Australia (postal symbol)
  • (i) Standards Australia
  • Sturmabteilung (German, "Storm Detachment", Nazi forerunner and rival of SS)
• S.A. – designation for a corporation in many European countries; see article for meanings
• SAA
  • (i) Saudi Arabian Airlines, former name of Saudia
  • Sex Addicts Anonymous
  • South African Airways
  • Southern Athletic Association
  • Standards Association of Australia, a former name of Standards Australia
• SAAB – (a) Svenska Aeroplan AB (Swedish aircraft manufacturer; also refers to its former auto manufacturing arm)
• SAAFR – (a/i) Standard use Army Aircraft Flight Route ("safer")
• SAAMI – (a) Sporting Arms and Ammunition Manufacturers' Institute ("sammy")
• SAARC – (i) South Asian Association for Regional Cooperation
• SAB – (i) Soprano Alto Baritone
• Sabena – (a) Société anonyme belge d'exploitation de la navigation aérienne (French for "Belgian Company for Exploiting Aerial Navigation", 1923–2001)
• SABIC – (p) Saudi Basic Industries Corporation
• SABR – (a) Society for American Baseball Research
• SAC
  • (a) Standards Activity Committee (of SISO)
  • U.S. Strategic Air Command (1946–1992)
• SACAT – (a) Semi Attended Customer Activated Terminal (Supermarket checkout)
• SACEUR – (p) Supreme Allied Commander EURope
• SACF - Semi Automatic Capsule Filler source
• SACLANT – (p) Supreme Allied Commander atLANTic
• SACLOS – (a) Semi-Automatic Command to Line of Sight
• SAD
  • (s) Safford Regional Airport (IATA code)
  • (a) Seasonal Affective Disorder
  • Situational Awareness Display
• SADD – (a) originally Students Against Drunk Driving, now Students Against Destructive Decisions (U.S. national school-related group)
• SADL
  • (a) Situation Awareness Data Link ("saddle")
  • Structural Architecture Description Language
• SADT - (i) Substance Abuse Day Treatment
• SAE
  • (i) Society of Automotive Engineers^[1]
  • Stamped addressed envelope
• SAFER – (a) Steel And Foam Energy Reduction
• SAFETY – (a) Stopping Adults Facilitating the Exploitation of Today's Youth
• SAFICT – (a) Software Agents as Facilitators of Interoperability in Collective Training
• sag – (s) Sango language (ISO 639-2 code)
• SAG
  • (a/i) Screen Actors Guild
  • Surface Action Group
• SAG-AFTRA – (a) Screen Actors Guild–American Federation of Television and Radio Artists
• SAGAT – (a) Situation Awareness Global Assessment Technique
• SAGE – (a) Semi-Automatic Ground Environment (simulation)
• SAHB – (a) Sensational Alex Harvey Band
• SAIC – (i) Science Applications International Corporation
• SALT
  • (a/i) Save A Life Today (SALT) Alert; Emergency Contact System
  • (a) Southern African Large Telescope
  • Strategic Arms Limitation Talks
• SAM
  • (a) Sequential-Access Memory
  • Sociedad Aeronáutica de Medellín
  • Surface-to-Air Missile
• Sambo – (p/a) Samooborona bez oruzhiya (Russian: "Самооборона без оружия", literally "self-defense without weapons")
• SAML – (a) Security Assertion Markup Language ("sam-ell")
• SANZAAR – (a) South Africa, New Zealand, Australia and Argentina Rugby
• san
  • (s) Sanskrit language (ISO 639-2 code)
  • (a) Storage Area Network
• SAO - (more than 20 alternatives)
• SAR
  • (s) Saudi riyal (ISO 4217 currency code)
  • (a) Search And Rescue
  • Special Administrative Region
  • Synthetic Aperture Radar
• SARA
  • (a) Southeastern Association for Research in Astronomy
  • Scientific Atlanta Resident Application
  • Scottish Amateur Rowing Association
  • Southern African Railway Association
  • State Administration for Religious Affairs
• SARP – (a) Search And Rescue Processor
• SARR – (i/a) Search And Rescue Repeater
• SARS – (a) Severe Acute Respiratory Syndrome
• SART
  • (a) Search and Rescue Transponder
  • Situational Awareness Rating Technique
• SARU – (i) South African Rugby Union
• SAS
  • (i) Scandinavian Airlines System
  • Second Avenue Subway
  • Situational Awareness System
  • Special Air Service
  • Studies, Analysis and Simulation
  • Side Angle Side
  • (a) Statistical Analysis System (original meaning; SAS Institute Inc. has evolved far beyond that scope)
• SASE – (i) Self-Addressed Stamped Envelope
• SASO – (a) Stability and Support Operations
• SASOL – (p) Suid Afrikaanse Steenkool en Oli.e. (Afrikaans, "South African Coal and Oil")
• SAT
  • (i) formerly Scholastic Aptitude Test and Scholastic Assessment Test; now known solely by the initials
  • Small Arms Trainer
• SATB – (i) Soprano Alto Tenor bass
• SATNAV – (p) Satellite Navigation (Increasingly common GPS based system in new vehicles)
• SATs – (a) Standard Assessment Tasks and other similar terms describing tests used in English schools; see National Curriculum assessment#Terminology
• SAU – (s) Saudi Arabia (ISO 3166 trigram)
• SAVAK – (a) Sazamane Etelaat va Amniate Kechvar (Iranian "Security and Intelligence Service")
• SAW
  • (i) ṣallā -llāhu ʿalayhī (wa-ʾālihī) wa-sallama (Arabic: صَلَّىٰ ٱللَّٰهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ, "God bless him [and his family] and grant him peace"), an honorific suffix within Islam for Muhammad
  • (a) Submerged arc welding
  • Squad Automatic Weapon
  • Surface acoustic wave
• SAWE – (a) Society of Allied Weight Engineers
• SAWS – (i) alternate form of the Islamic honorific suffix for Muhammad (see SAW)

• Sb – (s) Antimony (Latin Stibium)
• SbA - Stibarsen, an alloy of antimony and arsenic
• SB
  • (i) Sexy Bitch
  • Sexy Bastard
  • Sexy Boy (disambiguation)
  • (s) Solomon Islands (ISO 3166 digram)
  • (i) Special Warfare Boat Operator
• SBA
  • (i) Santa Barbara Airport
  • Simulation-Based Acquisition
  • Small Business Administration
  • Sovereign Base Area
  • Student bar association
• SBB – (i) German for the Swiss Federal Railways
• SBC
  • (i) Sensotronic Brake Control
  • Single-Board Computer
  • Southern Baptist Convention
  • Sun Belt Conference (US college sports)
• SBCCOM – (p) U.S. Army Soldier and Biological Chemical Command (disbanded 2003)
• SBCS – (i) Single-Byte Character Set
• SBCT – (i) Stryker Brigade Combat Team
• SBD
  • (s) Solomon Islands dollar (ISO 4217 currency code)
  • Silent But Deadly
• SBP
  • (i) Samahang Basketbol ng Pilipinas (Filipino, "Basketball Federation of the Philippines")
  • U.S. School Breakfast Program
  • Society of Business Practitioners
  • State Bank of Pakistan
• SBS
  • (i) Special Boat Service
  • Special Broadcasting Service
  • Seoul Broadcasting System
• SBW
  • (i) Sonny Bill Williams (New Zealand dual-code rugby player)

• sc – (s) Sardinian language (ISO 639-1 code)
• Sc – (s) Scandium
• SC
  • (s) Cruiser Submarine (US Navy hull classification) c Saint Kitts and Nevis (FIPS 10-4 country code; from Saint Christopher)
  • Seychelles (ISO 3166 digram)
  • South Carolina (postal symbol)
• SCA
  • (i) Service Contract Act
  • Sexual Compulsives Anonymous
  • Society for Creative Anachronism
• SCAP – (a) Supreme Commander Allied Powers (Allied occupation of Japan)
• sccm – (s) Standard cubic centimetre per minute (unit of measurement of fluid flow)
• sccs – (s) Standard cubic centimetre per second (unit of measurement of fluid flow)
• scfh – (s) Standard cubic foot per hour (unit of measurement of fluid flow)
• scfm – (s) Standard cubic foot per minute (unit of measurement of fluid flow)
• scfs – (s) Standard cubic foot per second (unit of measurement of fluid flow)
• SCG – (s) Serbia and Montenegro (ISO 3166 trigram; defunct since 2006)
• SCHIMS – (i) Soldier Combat Helmet Identification Marking System
• SCHIP – (a) State Children's Health Insurance Program (U.S.; often pronounced "ess-chip")
• SciFi – Science Fiction
• sCJD – (i) Sporadic Creutzfeldt–Jakob disease
• SCM – (i) Surface Contamination Module
• SCMODS – (s) State, County, Municipal Offender Data System
• SCN – (p) Suprachiasmatic Nucleus
• SCNT – (i) Somatic Cell Nuclear Transfer
• SCO
  • (i) Santa Cruz Operation (initials later used by SCO Group)
  • (s) Scotland (FIFA trigram; not eligible for an ISO 3166 or IOC trigram)
  • (a) Shanghai Cooperation Organisation
• SCOTUS – (a) Supreme Court of the United States
• SCR – (s) Seychelles rupee (ISO 4217 currency code)
• SCRAM – (a) Safety Control Rod Axe Man
• SCS
  • (i) Scan Correlated Shift
  • Soil Conservation Service
• SCSI
  • (a) Small Computer System Interface ("scuzzy")
  • (i) Strategic and Combat Studies Institute
• SCT – (s) Scattered Sky (METAR Code)
• SCTP – (i) Stream Control Transmission Protocol
• Scuba – (a) Self Contained Underwater Breathing Apparatus
• SCUF – Slow Continuous Ultrafiltration
• SCUFN – (i) Sub-Committee on Undersea Feature Names (of GEBCO)

• sd – (s) Sindhi language (ISO 639-1 code)
• SD
  • (i) Secure Digital (memory card format)
  • Sheriff's department
  • Smoke/Decontamination
  • (s) South Dakota (postal symbol)
  • Sudan (ISO 3166 digram)
• SDC
  • (i) Shaft Driven Compressor
  • U.S. Army Strategic Defense Command (1985–1992)
• SDG – (s) Sudanese pound (ISO 4217 currency code)
• SDG – (i) Sum Dum Goy - greasy spoon chinese restaurant
• SDH – (i) Synchronous Digital Hierarchy
• SDHC – (i) Secure Digital High Capacity
• SDI – see entry
• SDN – (s) Sudan (ISO 3166 trigram)
• SDO – (i) Scattered Disc Object
• SDP – (i) Social Democratic Party (European politics)
• SDR – (i) Strategic Defence Review
• SDRAM – (i) Synchronous Dynamic Random-Access Memory ("ess-dee-ram")
• SDS – (i) Students for a Democratic Society
• SDSS – (i) Sloan Digital Sky Survey
• SDXC – (p) Secure Digital eXtended Capacity

• se – (s) Northern Sami language (ISO 639-1 code)
• Se – (s) Selenium
• SE
  • (s) Seychelles (FIPS 10-4 country code)
  • (i) Societas Europaea (form of business organization in the EU)
  • South-east
  • (s) Sweden (ISO 3166 digram)
  • (i) Synthetic Environment
  • System Engineering
• SEAD – (i) Suppression of Enemy Air Defence(s)
• SEADI – (i) Senior Executioner of Approved Driving Instructors
• SEAFDEC – (p) Southeast Asian Fisheries Development Center
• SEAL – (p) SEa-Air-Land
• SEAT – (a) Sociedad Española de Automóviles de Turismo (Spanish for "Spanish Touring Car Company")
• SEATO – (a) Southeast Asia Treaty Organization
• SeaWiFS – (p) Sea-Viewing Wide Field of View Sensor (satellite instrument)
• SEC
  • (i) U.S. Securities and Exchange Commission
  • (p) Security
  • Southeastern Conference
• SECaaS - (p) Security-as-a-Service
• SECAM – (a) Séquentiel couleur à mémoire (French for "Colour Sequential with Memory"; TV standard, cf. NTSC, PAL)
• SECDEF – (p) (U.S.) Secretary of Defense
• SED – (i) CERDEC Software Engineering Directorate
• SEDRIS – (a) Synthetic Environment Data Representation and Interchange Specification
• SEE – (a) Small Emplacement Excavator
• SEG – (i) Society of Exploration Geophysicists
• SEG – (i) Special Escort Group
• SEK – (s) Swedish krona (ISO 4217 currency code)
• Selkent – (p) South East London & Kent Bus Company
• SELT – (a) Single Ended Line Test (ing)
• SEM
  • (i/a) Sensor Employment Manager
  • Switch to Email Mode, i.e. stop texting as it is more disruptive by making a sound or vibrating and email instead, for a given time
• SEN
  • (s) Senegal (ISO 3166 trigram)
  • (i) Small Extension Node
• SEP
  • (i) Somebody Else's Problem
  • Spherical Error Probable
  • System Enhancement Package
  • System Engineering Plan
• SEPTA – (i) Southeastern Pennsylvania Rapid-Transit Authority
• SERE – (i) Survival, Evasion, Resistance and Escape
• SESSPE – (a) Submarine Escape and Surface Survival Personnel Equipment
• SET – (p) Staphylococcal EnteroToxin
• SETI – (a) Search for ExtraTerrestrial Intelligence
• SETAC – (a) Society for Environmental Toxicology and Chemistry
• SEU
  • (i) Single Event Upset (solid state physics)
  • Slightly Enriched Uranium
  • Special Evidence Unit

• SF
  • (s) Fleet Submarine (retired US Navy hull classification)
  • (i) San Francisco
  • Science fiction
  • (s) South Africa (FIPS 10-4 country code)
  • (i) Speculative fiction
  • Special Forces
• SFA
  • (i) Sales force automation
  • Saturated fatty acid
  • Scottish Football Association
  • Stephen F. Austin (State University)
  • Sudan Football Association
• SFE
  • (i) Supercritical fluid extraction
  • Sydney Futures Exchange
• SFF – (i) Standard File Format
• sf&f – (i) Science fiction & fantasy
• SFIO
  • (i) French Section of the Workers' International (former party)
  • (i) Serious Fraud Investigation Office (India)
• SFM – Switch to Facebook Mode, i.e. to message someone on Facebook instead of texting as it is less disruptive in the sense of the phone not making sound or vibrating, for a period of time
• SFOB – (i) Special Forces Operations Base
• SFOR – (p) UN Stabilisation Force (in Bosnia and Herzegovina)
• SFU – (i) Simon Fraser University (Canada)

• sg – (s) Sango language (ISO 639-1 code)
• Sg – (s) Seaborgium
• SG
  • (s) Senegal (FIPS 10-4 country code)
  • Singapore (ISO 3166 digram)
  • Snow Grains (METAR Code)
  • (i) Study Group
• SGC
  • (i) Server Gated Cryptography
  • (p) Stargate Command
• SGD – (s) Singapore dollar (ISO 4217 currency code)
• SGML – (i) Standard Generalized Markup Language
• SGP – (s) Singapore (ISO 3166 trigram)
• SGS
  • (s) South Georgia and the South Sandwich Islands (ISO 3166 trigram)
  • (i) Svalbard Ground Station (Landsat)
  • Société Générale de Surveillance

• SH
  • (s) Saint Helena (ISO 3166 digram)
  • (p) SONATRACH (Algerian petroleum company)
  • Shanghai
• SHAC
  • (a) Stop Huntingdon Animal Cruelty
  • Student Health Action Coalition
• SHAPE – (a) Supreme Headquarters Allied Powers Europe
• SHF – (i) Super High Frequency
• SHN – (s) Saint Helena (ISO 3166 trigram)
• SHO – (a) Showtime (see also sho.com)
• SHOALS – (a) Scanning Hydrographic Operational Airborne Lidar Survey
• SHORAD – (p) Short Range Air Defence
• SHORADEZ – (p) SHORAD Engagement Zone
• SHP – (s) Saint Helena pound (ISO 4217 currency code)
• SHRA – (s) Rain Showers (METAR Code)
• SHSN – (s) Snow Showers (METAR Code)

• si – (s) Sinhala language (ISO 639-1 code)
• Si – (s) Silicon
• SI
  • (s) Slovenia (ISO 3166 and FIPS 10-4 country code digram)
  • (i) Socialist International
  • Sports Illustrated
  • Système International (French, International System of Units)
• SIA – (s) Singapore Airlines (ICAO code)
• SIA – (i) Survivors of Incest Anonymous
• SIAM – (i) Society for Industrial and Applied Mathematics
• SIC – (a) Standard Industrial Classification
• SICS – (a/i) Swedish Institute of Computer Science
• SIDS – (a) Sudden infant death syndrome
• SIDU – (i) select, insert, delete, update. See Create, read, update and delete
• SIF – (i) Selective Identification Feature
• SIFF – (i) Successor IFF
• SIG
  • (i) Schweizerische Industrie Gesellschaft (German, "Swiss Industry Company"). See also SIG Sauer, a firearms manufacturer spun off from the aforementioned company in 2000.
  • (p) .signature (UNIX shell/Internet standard file name)
  • (a/i) Special Interest Group
  • (a/i) Strasbourg Illkirch-Graffenstaden Basket (French basketball club)
• SIGCAT – (a) Special Interest Group for CD-ROM Applications and Technology
• SIGINT – (p) Signals Intelligence
• SIGMET – (p) Significant Meteorological Information
• SIIT
  • (i) Saskatchewan Indian Institute of Technologies (Canadian university)
  • Sirindhorn International Institute of Technology (Thai university)
  • Stateless IP/ICMP Translation algorithm
• SIMAC – (a) Semantic Interaction with Music Audio Contents
• SIMLAS – (p) Soldier Integrated Multipurpose Laser System
• SIMM – (a) Single In-line Memory Module
• SIMNET – (p) SIMulator NETwork, later SIMulation NETwork
• SIMNET-D - (p) SIMNET-Developmental
• SIMP – (a) Strongly Interacting Massive Particle
• SIMPLE
  • (a) Satellite Interactive Multimedia Platform for Low-cost Earth stations
  • (p) Savings Incentive Match Plan for Employees (as used in SIMPLE IRA)
  • (a) Standard Interface for Multiple Platform Link Evaluation (NATO STANAG 5602)
• sin – (s) Sinhala language (ISO 639-2 code)
• SIN – (a) Social insurance number (Canada)
• SINCGARS – (p) SINgle Channel Ground and Airborne Radio System
• SIP
  • (i) Session Initiation Protocol
  • State Implementation Plan
  • System Improvement Program
  • Systematic investment plan
• SIPP – (a) Self-Invested Personal Pension
• Siri – (a) Speech Interpretation and Recognition Interface (Apple iOS software)
• SIRI – (a) Service Interface for Real Time Information
• SIRS — (a) Systemic inflammatory response syndrome
• SiS – (i) Silicon Integrated Systems
• SIS – (i) UK Secret Intelligence Service (also known as MI6)
• SISO
  • (a) Simulation Interoperability Standards Organization
  • Society of Independent Show Organizers
• SIW – (i) Simulation Interoperability Workshop
• SIYSS – (i) Stockholm International Youth Science Seminar

• SJ
  • (s) Svalbard and Jan Mayen (ISO 3166 digram)
  • (i) Societas Iesu (Latin: The Society of Jesus, the Jesuit order)
  • (i) Statens Järnvägar (Swedish State Railways)
• SJA – (i) Staff Judge Advocate (military law)
• SJC – (i) Supreme Judicial Court of Massachusetts (note: the highest court in the state of Maine is also called the Supreme Judicial Court)
• SJM – (s) Svalbard and Jan Mayen (ISO 3166 trigram)
• SJW – (i) Social Justice Warrior

• sk – (s) Slovak language (ISO 639-1 code)
• SK
  • (s) Saskatchewan (postal symbol)
  • Slovakia (ISO 3166 digram)
• SKC – (s) Clear Sky (METAR Code)
• SKK – (s) Slovak koruna (ISO 4217 currency code)
• SKM – (s) Sikkim (ISO 3166 trigram; obsolete 1975)
• SKU - (i) Stock Keeping Unit

• sl – (s) Slovene language (ISO 639-1 code)
• SL
  • (s) Sierra Leone (ISO 3166 and FIPS 10-4 country code digram)
  • (i) Start Line
• SLA
  • (i) Service Level Agreement
  • Symbionese Liberation Army
• SLAA – (i) Sex and Love Addicts Anonymous
• SLAC – (a) Stanford Linear Accelerator Center
• SLAN – (i) sine loco, anno, nomine (Latin, "without place, year, or name")
• SLAP – (a) Saboted light armor penetrator (type of firearms ammunition)
• SLAPP – (a) Strategic lawsuit against public participation
• SLB – (s) Solomon Islands (ISO 3166 trigram)
• SLBM – (i) Sea/Submarine-Launched Ballistic Missile
• SLC – (i) Scan Line Corrector
• SLE – (s) Sierra Leone (ISO 3166 trigram)
• SLI/SLi
  • (i/s) Scan-Line Interleave
  • Scalable Link Interface
• SLIT – (p) SubLingual ImmunoTherapy
• slk – (s) Slovak language (ISO 639-2 code)
• SLL – (s) Sierra Leone leone (ISO 4217 currency code)
• SLO – (s) Slovenia (IOC trigram, but not FIFA or ISO 3166)
• SLOC
  • (a) Sea Lines Of Communication
  • Source Lines Of Code
• SLORC – (a) State Law and Order Restoration Council (of Burma)
• SLP
  • (i) Sea Level Pressure
  • (i) Super Long Play
• slph – (s) Standard litre per hour (air flow)
• slpm – (s) Standard litre per minute (air flow)
• slps – (s) Standard litre per second (air flow)
• SLR – (i) Single-Lens Reflex (camera)
• SLT
  • (i) Single Lens Translucent
  • (i) Speech and language therapist
  • (i) Solid Logic Technology (electronics)
  • Swing Landing Trainer (paratroops)
  • (i) Secondary lymphoid tissue
• slv – (s) Slovenian language (ISO 639-2 code)
• SLV – (s) El Salvador (ISO 3166 trigram)

• sm – (s) Samoan language (ISO 639-1 code)
• Sm – (s) Samarium
• SM
  • (i) Sado-Masochism
  • (s) San Marino (ISO 3166 and FIPS 10-4 country code digram)
  • (i) Soldier's Manual
  • (s) Submarine Minelayer (US Navy hull classification)
• SMA – (i) Scan Mirror Assembly
• SMART - many different meanings
• SMASS – (a) Small Main-Belt Asteroid Spectroscopic Survey
• SMCT – (i) Soldier's Manual of Common Tasks
• SMD – (i) Surface Mount Device
• SMDR – (i) Station Message Detail Recording
• sme – (s) Northern Sami language (ISO 639-2 code)
• SME
  • (i) Scan Mirror Electronics
  • Subject Matter Expert
• SMG
  • (i) Sequential Motorsport Gearbox
  • SubMachine Gun
• SMH – (a) Shaking My Head
• SMil – (a) Sadomasochisterne i landet (Danish SM organisation)
• SMIL – (a) Synchronized Multimedia Integration Language
• smo – (s) Samoan language (ISO 639-2 code)
• SMP – (i) Standard Military Pattern
• SM&R – (i) Source, Maintenance, and Recoverability
• SMR – (s) San Marino (ISO 3166 trigram)
• SMS – many, including: Short message service; see entry
• SMTP – (i) Simple Mail Transfer Protocol
• SMU – (i) Southern Methodist University
• SMX
  • many, including: (i) Server Macro Expansion
  • (p) Solaris MINIX
  • (p) Spatial multiplexing
  • (p) Sulfamethoxazole; see entry
• SMZ
  • many, including: (i) Silver Mt. Zion
  • (p) Sulfamethazine
  • (p) Sulfamethoxazole; see entry

• sn – (s) Shona language (ISO 639-1 code)
• Sn – (s) Tin (Latin Stannum)
• SN
  • (s) Senegal (ISO 3166 digram)
  • Singapore (FIPS 10-4 country code)
  • Snow (METAR Code)
  • SuperNova
  • Screen Name
• sna – (s) Shona language (ISO 639-2 code)
• SNAFU – (a) "Situation Normal — All Fouled/Fucked Up"
• SNAP – (p) Supernova/Acceleration Probe
• SNCB – (i) Société nationale des chemins de fer de Belgique (French for "Belgian Railways National Society", NMBS in Dutch)
• SNCF – (i) Société nationale des chemins de fer français (French for "French Railways National Society")
• snd – (s) Sindhi language (ISO 639-2 code)
• SND – (i) Standard Nomenclature Database
• SNE – (i) Synthetic Natural Environment
• SNES – Super Nintendo Entertainment System
• SNÉTA – (a) Syndicat national pour l'étude des transports aériens (French for "Aerial transport Study National Syndicate", 1919–1923)
• SNG – (i) Satellite News Gathering (television)
• SNL
  • (i) Saturday Night Live (television)
  • (i) Società Navigazione del Lago di Lugano
• SNM – (i) Special Nuclear Material
• SNMP – (i) Simple Network Management Protocol
• SNOBOL – (p) StriNg Oriented symBOlic Language
• SNP – (i) Single-nucleotide polymorphism
• SNR
  • (i) SuperNova Remnant
  • Signal-to-Noise Ratio
• SNRI – (i) Serotonin-Norepinephrine Reuptake Inhibitor
• SNS – (i) Spallation Neutron Source
• SNU – (i) Solar Neutrino Unit

• so – (s) Somali language (ISO 639-1 code)
• SO
  • (i) Shared Object (Unix)
  • Sheriff's Office
  • Significant other
  • (s) Somalia (ISO 3166 and FIPS 10-4 country code digram)
• SOA
  • (a) service-oriented architecture
  • (a) Society of Actuaries
  • (i) State of the art
• SOAP
  • (a) Simple Object Access Protocol
  • Supplemental Offer and Acceptance Program (U.S. medical residency matching)
• SOB
  • (i) Son Of a Bitch
  • Same Old Bullshit
• SOC – (a) Sector Operations Centre
• Soccsksargen – (p) South Cotabato, Cotabato, Sultan Kudarat, Sarangani, General Santos (a region in the Philippines; pronounced "sock-sar-gen")
• SOCOM – (p) (U.S.) Special Operations Command
• SoCon – (p) Southern Conference (U.S. college sports)
• SOD
  • (i/a) School Of Dentistry
  • Statement Of Difference(s)
  • Statement Of Direction
  • Statement Of Documentation
  • Statement Of Duty/Duties
• SOE
  • (i) Secret Of Evermore
  • Special Operations Executive (WWII British organization)
  • State Of Emissions (EW)
• SOF
  • (a/i) Special Operations Force(s)
  • Status of Forces
• SOFIA – (a) Stratospheric Observatory For Infrared Astronomy
• SOGAT
  • (a) Society of Graphical and Allied Trades
  • Former British printing union
• SOHC – (i) Single-OverHead-Cam engine
• SOHO – (p) Solar and Heliospheric Observatory
• SOI
  • (i) Signal Operating Instruction
  • (i) Southern Oscillation Index
• SOL – (i) Shit Out of Luck
• SOLIS – (i) Synoptic Optical Long-term Investigations of the Sun
• som – (s) Somali language (ISO 639-2 code)
• SOM
  • (a) Simulation Object Model
  • (s) Somalia (ISO 3166 trigram)
• Sonar – (p) SOund Navigation And Ranging
• SOP
  • (i) Standing/Standard Operating Procedure
  • State of Play
• SOR
  • (i) State Of Readiness
  • Statement Of Requirements
• SOS
  • (s) Somali shilling (ISO 4217 currency code)
  • Save Our Souls
• SOSTAR – (a) Stand-Off Surveillance and Target Acquisition Radar
• sot – (s) Sotho language (ISO 639-2 code)
• SOUTHAG – (p) Southern Army Group
• SOUTHCOM – (p) (U.S.) Southern Command
• SOV – (i) Single Occupant Vehicle
• SOW – (i) Statement Of Work
• SOWHAT – (p) RESNA Subcommittee on Wheelchairs and Transportation
• SOX – (p) Sarbanes–Oxley Act

• Sp
  • (p) Special
  • Spring tide (nautical charts)
  • (i) sine prole (Latin, "without offspring")
• SP
  • (i) Security Police
  • Self-Propelled
  • Shore Patrol
  • (s) Spain (FIPS 10-4 country code)
  • (i) Start Point
  • Strong Point
• spa – (s) Spanish language (ISO 639-2 code)
• SPA - Single Page Application
• SPAAG – (a) Self-Propelled Anti-Aircraft Gun
• SPAC - Saratoga Performing Arts Center
• SPACECOM – (p) (U.S.) Space Command
• SPAL – (a) Società Polisportiva Ars et Labor ("Art & Labor Sports Club", with the "SP" from Italian and "AL" from Latin), Italian football club
• Spaser – (a) Surface plasmon amplification by stimulated emission of radiation
• SPC – (i) Secretariat of the Pacific Community
• SPCA - Society for the Prevention of Cruelty to Animals
• SPCO – (i) Single-Pole Change Over
• SPD
  • (i) Shimano Pedaling Dynamics
  • Sozialdemokratische Partei Deutschlands (Social Democratic Party of Germany)
• SPDT – (i) Single-Pole Double-Throw
• SPEAC – (a) Stop Primate Experiments at Cambridge (later became SPEAK)
• SPECTRE – SPecial Executive for Counter-intelligence, Terrorism, Revenge and Extortion
• S.P.E.A.R. - Spontaneous Protection Enabling Accelerated Response
• SPEED – (a) Subsistence Preparation by Electronic Energy Diffusion (early military microwave oven)
• SPIE – (i) originally the Society for Photo-Optical Instrumentation Engineers ("SPIE – The International Society for Optical Engineering" 1981–2007, "SPIE" since 2007)
• SPL
  • (i) Scottish Premier League
  • Superior Parietal Lobule
  • Sound pressure level
• SPM – (s) Saint Pierre and Miquelon (ISO 3166 trigram)
• SPOD – (a/i) Sea Port of Debarkation
• SPOE – (a/i) Sea Port of Embarkation
• SPOT – (a) Satellite pour l'observation de la Terre (French, "Satellite for Earth Observation")
• SPQR – (i) Senatus Populusque Romanus (Latin "The Senate and the People of Rome")
• sps – (i) sine prole superstite (Latin, "without surviving issue")
• SPS – (i) Standard Positioning Service (GPS)
• SPST – (i) Single-Pole Single-Throw

• sq – (s) Albanian language (ISO 639-1 code)
• SQ – (i) Sound Quality
• SQ – (i) Standard Quality
• sqi – (s) Albanian language (ISO 639-2 code)
• SQL – (i/a) Structured Query Language ("seek-well")
• SQS - Amazon Simple Queue Service
• SQUID – (p) Superconducting QUantum Interference Device
• SQOR – (p) Succinate:Quinone OxidoReductase, enzyme superfamily including quinone-linked succinate dehydrogenase and fumarate reductase

• sr – (s) Serbian language (ISO 639-1 code)
• Sr – (s) Strontium
• SR
  • (i) Sound Reinforcement
  • Supply Route
  • (s) Suriname (ISO 3166 digram)
  • (i) Sveriges Radio (Swedish Radio Ltd)
• SR – (i) Sustained release of a drug
• SRAM
  • (p) Scott (King), Ray (Day), SAM (Patterson) — founders of bicycle component manufacturer SRAM Corporation
  • (p) Static Random Access Memory ("ess-ram")
• SR-ATGW – (i) Short-Range Anti-Tank Guided Weapon
• SRB – (i) Solid Rocket Booster
• SRBM – (i) Short-Range Ballistic Missile (cf. IRBM, ICBM)
• SRC – (i) Scheduled Removal Component
• srd – (s) Sardinian language (ISO 639-2 code)
• SRD
  • (i) Science Requirements Document
  • (s) Surinam dollar (ISO 4217 currency code)
• SRE - (i) Site Reliability Engineer(ing)
• SREL – (i) Savannah River Ecology Laboratory
• SRG
  • (i) SACEUR Rover Group
  • Special Republican Guard
• SRGW – (i) Short-Range Guided Weapon
• SRL
  • (i) Savannah River Laboratory
  • Single Rocket Launcher
  • Survival Research Labs
• SRM – (i) Specified Risk Material(s)
• srp – (s) Serbian language (ISO 639-2 code)
• SRS – (i) Savannah River Site
• SRTP – (i) [Secure Real-time Transport Protocol]

• ss – (s) Swati language (ISO 639-1 code)
• SS
  • (s) Sand Storm (METAR Code)
  • (p) Schutzstaffel (German, roughly "Protection Squadron"; Nazi elite Praetorian guard)
  • (i) U.S. Secret Service
  • Spanish Ship
  • Stainless steel
  • Stockholm Skins
  • (s) Submarine (US Navy hull classification)
  • (i) Super Sport
  • Surface-to-Surface (missile)
• SSA
  • (s) Cargo Submarine (US Navy hull classification)
  • (i) Social Security Administration (U.S.)
  • Statistics South Africa
• SSB – (a) Single-sideband modulation
• SSB – (i) Sacramento Sustainable Business
• SSBN – (s) Nuclear-Powered Ballistic Missile Submarine (US Navy hull classification)
• SSC
  • (i) Safe, Sane, Consensual (SM phrase)
  • Secondary Somatosensory Cortex
  • Smaller-Scale Contingency
  • U.S. Army Soldiers System Center (Natick, Massachusetts)
  • Superconducting Super Collider
• SSCCATAGAPP – Singles, Seniors, Childless Couples, And Teens And Gays Against Parasitic Parents (fictional organization from The Simpsons)
• SSD
  • (i) Solid-state drive
  • (s) South Sudan (ISO 3166 trigram)
• SSDC – (i) U.S. Space and Strategic Defense Command
• SSDD
  • (i) Same Shit, Different Day
  • Single-Sided Double-Density (floppy disk)
• SSE
  • (s) South-southeast
  • (i) Streaming SIMD Extensions
• SSG – (s) Guided Missile Submarine (retired US Navy hull classification)
• SSGN – (s) Nuclear-Powered Guided Missile Submarine (US Navy hull classification)
• SSH – (i) Saffir-Simpson Hurricane scale
• SSK – (s) Hunter-Killer Submarine (retired US Navy hull classification)
• SSKP – (i) Single-Shot Kill Probability
• SSL – (i) Secure Sockets Layer
• SSM – (i) Surface-to-Surface (Guided) Missile
• SSN
  • (s) Nuclear-Powered Attack Submarine (US Navy hull classification)
  • (i) SIM Serial Number
  • Social Security Number (U.S.)
  • Socialist Solidarity Network
  • Subsystem number (SCCP, SS7)
• SSNW – (i) Same Shit, New Wrapping
• SSO – (s) Submarine Oiler (retired US Navy hull classification)
• SSP – (s) Submarine Transport (retired US Navy hull classification)
• SSR
  • (s) Radar Picket Submarine (retired US Navy hull classification)
  • (i) Solid State Recorder
• SSRI
  • (i) Selective Serotonin Reuptake Inhibitor
  • Social Systems Research Institute
• SSRN
  • (i) Social Science Research Network
  • (s) Nuclear-Powered Radar Picket Submarine (retired US Navy hull classification)
• SSS
  • (i) Siding Spring Survey
  • Side Side Side (an acronym for remembering congruent triangles)
  • (i) Sigue Sigue Sputnik (band)
• S/SSM – (i) Surface-to-Subsurface Missile
• SST
  • (i) SuperSonic Transport
  • (s) Training Submarine (US Navy hull classification)
  • Saturated Suction Temperature (refrigeration cycles)
• SSTO – (i) Single-Stage To Orbit
• SSV – (i) Soft-Skinned Vehicle (i.e., unarmoured)
• ssw – (s) Swati language (ISO 639-2 code)
• SSW – (s) South South-West

• st – (s) Sotho language (ISO 639-1 code)
• ST
  • (s) Saint Lucia (FIPS 10-4 country code)
  • São Tomé and Príncipe (ISO 3166 digram)
• STA
  • (i) Scheduled Time of Arrival
  • Surveillance and Target Acquisition
• STAG – (a) (U.S.) Strategy and Tactics Group
• STAGE – (a) Scenario Toolkit And Generation Environment
• STANAG – (p) (NATO) Standardisation Agreement
• STAR
  • (a) Scientific and Technical Aerospace Reports (NASA)
  • Simulation of Tactical Alternative Responses
  • Special Threat Analysis and Recognition
• STAT
  • (a) Signal Transducers and Activators of Transcription (cell biology)
  • Special Tertiary Admissions Test (Australia)
• STB - Surface Transportation Board^[2]
• STC – (i) Superior Temporal Cortex
• S&TCD – (i) CERDEC Space and Terrestrial Communications Directorate
• STD
  • (s) São Tomé and Príncipe dobra (ISO 4217 currency code)
  • (i) Sexually Transmitted Disease
• STDM – (i) Statistical Time Division Multiplexing
• STEM
  • (a) Scanning transmission electron microscopy
  • Science, technology, engineering, and mathematics
  • (p) Spatiaotemporal Epidemiological Modeler (IBM-developed software)
• STENTOR – (p) Satellite de télécommunications pour expérimenter de nouvelles technologies en orbite (French, "Orbital New Technology Experimental Telecommunications Satellite")
• STFU
  • (i) Southern Tenant Farmers Union
  • Stuff You^{[citation needed]}
  • "Shut the fuck up!"
• STH – Sonic the Hedgehog
• STI
  • (i) Sexually Transmitted Infection
  • Subaru Tecnica International
• STK – (i) Satellite Tool Kit
• STM – (i) Short Term Memory
• STOL – (i) Short Take-Off and Landing
• STOVL – (i) Short Take-Off and Vertical Landing
• STP
  • (s) São Tomé and Príncipe (ISO 3166 trigram)
  • (i) Standard Temperature and Pressure
• STR – (i) Short Tandem Repeat (DNA analysis)
• STRATCOM – (p) United States Strategic Command
• STRICOM
  • (p) U.S. Army Simulation, Training & Instrumentation Command (1992–)
  • Strike Command (1962–1971)
• STRIVE – (a) Synthetic Tactical Real-time Interactive Virtual Environment
• STSM – (i) Senior Technical Staff Member
• Stuka – (p) Sturzkampfflugzeug (German WWII dive bomber)

• su – (s) Sundanese language (ISO 639-1 code)
• SU
  • (s) Soviet Union (ISO 3166 digram; obsolete 1992)
  • Sudan (FIPS 10-4 country code)
• SUB – (i) Student Union Building
• SuD – (a) Subject under Discussion
• SUDC – Swedish United Dawah Center, a salafist Islamic organisation in Sweden
• SUI
  • (a) Sonic user interface
  • (s) Switzerland (IOC and FIFA trigram, but not ISO 3166)
• SUK – Start Up Kit
• sun – (s) Sundanese language (ISO 639-2 code)
• SUN – (s)
  • Soviet Union (ISO 3166 trigram; obsolete 1992)
  • Stanford University Network that led to Sun Microsystems
• SUNY – (a) State University of New York (usually pronounced "sue-knee")
• SUR – (s) Suriname (ISO 3166 trigram)
• SURTASS – (p) Surveillance Towed Array Sensor System
• SUSAT – (a) Sight Unit Small Arms, Trilux
• SUV – (i) Sport Utility Vehicle

• sv – (s) Swedish language (ISO 639-1 code)
• SV
  • (s) El Salvador (ISO 3166 digram)
  • (p) Sportverein (German for "Sport Association", as in Hamburger SV and SV Werder Bremen)
• SVC – (i) Secondary Visual Cortex
• SvD – (p) Svenska Dagbladet (Swedish newspaper)
• SVD
  • (i) Singular Value Decomposition
  • Snaiperskaya Vintovka Dragunova (Снайперская винтовка Драгунова, Russian for "Dragunov Sniper Rifle")
• SVG – (i) Scalable Vector Graphics
• SVK – (s) Slovakia (ISO 3166 trigram)
• SVM
  • (p) Stroboscopic effect Visibility Measure; a measure for assessing a type of temporal light artefacts
  • (i) Support Vector Machine (artificial intelligence)
• SVN – (s) Slovenia (ISO 3166 and FIFA trigram)
• SVO – (i) subject–verb–object
• SVR – (i) Sluzhba Vneshney Razvedki (Служба Внешней Разведки, Russian for "Foreign Intelligence Service")

• sw – (s) Swahili language (ISO 639-1 code)
• SW
  • (s) South-West ordinal direction
  • Sweden (FIPS 10-4 country code)
  • (a) Shortwave
  • Star Wars
• swa – (s) Swahili language (ISO 639-2 code)
• SWA
  • (i/a) Secure Web Access
  • South-West Asia
• SWAC – (p) Southwestern Athletic Conference
• SWAG
  • Scientific wild-ass guess, slang for a rough estimate based on expert experience
  • Sourceware Archive Group, a free collection of classified source code and sample programs written in Pascal
  • Sport Writers Association of Ghana, Sports Writers Association based in Ghana
  • Special Warfare Group, a former name used by the Naval Special Operations Command
  • "Supporters Without A Game", sport slang spun off from WAGs ("wives and girlfriends")
• SWALK – (a) Sealed With A Loving Kiss
• SWAN – (a) System for Wearable Audio Navigation
• SWAP – (a) Surface Waters Acidification Programme
• SWAPO – (a) South-West Africa People's Organisation
• SWAT – (a) Special Weapons And Tactics
• swe – (s) Swedish language (ISO 639-2 code)
• SWE – (s) Sweden (ISO 3166 trigram)
• SWF
  • (p) Shockwave Flash file ("swiff")
  • Single White Female
• SWG
  • (i) Surface Warfare Group
  • Symbology Working Group
• SWHR – (i) Society for Women's Health Research
• SWIG – (a) Simplified Wrapper and Interface Generator
• SWIR – (a/i) Short Wave InfraRed ("ss-why-are" or "swhirr")
• SWLABR – (i) "She Was Like A Bearded Rainbow", a song by the band Cream
• SWORD – (p) Subjective WORkload Dominance
• SWORDS – (a) Special Weapons Observation Reconnaissance Detection System
• SWOT – (a) Strengths, Weaknesses, Opportunities, Threats (mnemonic)
• SWP
  • (i) Special Working Party ("swipp")
  • Systematic Westing Plan (a plan of periodic westing of shares or mutual funds worth a fixed amount of money)
  • Skill with prize (UK pub quiz machines — quality titles include: Pub Quiz, Quiz City, Frog in a Liquidizer, Who Wants To Win a Tenner?)
• SWT – (i) Sea Water Tank
• SWV – (i) Sisters With Voices (American female R&B vocal group)
• SWZ – (s) Swaziland (ISO 3166 trigram)

• SX – (i) Sonic X
• SXM
  • (s) Sint Maarten (ISO 3166 trigram)
  • (i) Stream X-Machine

• SY – (s) Syria (ISO 3166 and FIPS 10-4 country code digram)
• SYC – (s) Seychelles (ISO 3166 trigram)
• SYLK – Microsoft 'Symbolic Link' data file format
• SYP – (s) Syrian pound (ISO 4217 currency code)
• SYR – (s) Syria (ISO 3166 trigram)
• Syriza – (p) Synaspismós Rizospastikís Aristerás (Greek Συνασπισμός Ριζοσπαστικής Αριστεράς, "Coalition of the Radical Left")
• SysML – (p) System Modeling Language
• Sysop – (p) System Operator

• SZ
  • (s) Swaziland (ISO 3166 digram)
  • Switzerland (FIPS 10-4 country code)
• SZL – (s) Swaziland lilangeni (ISO 4217 currency code)