S

s

second (also sec.) (the SI base unit for time)

S/MIME

Secure MIME

S/W

Software (the slash is optional)

SAINT

Strategic Artificially Intelligent Nuclear Transport (Short Circuit)

SALT

Strategic Arms Limitation Talks

SAN

Storage Area Network

SAS

Special Air Service

SAS

Scandinavian Airlines System

SAS

Statistical Analysis System

SASE

Self-Addressed Stamped Envelope

SAT

Scholastic Aptitude Test

SAT

Small Aperture satellite Terminal

SCAG

Spectrographic Color Attribute Generator (The X-Files #7ABX06)

SCHMODS

State County Municipal Offender Data System (The Blues Brothers)

SCO

Santa Cruz Operation

SCSI

Small Computer Systems Interface

SCUBA

Self-Contained Underwater Breathing Apparatus (from DPB)

SDDS

Sony Dynamic Digital Sound

SDH

Synchronous Digital Hierarchy

SDMI

Secure Digital Music Initiative

SDRAM

Synchronous DRAM

SE

Special Edition

SEI

Software Engineering Institute

SEI

Sustainable Ecosystems Institute

SEI

Silicon Engineering, Inc.

SET

Secure Electronic Transaction

SETI

Search for ET Intelligence

SF

Science Fiction

SF

Samantha Fox

SGI

Silicon Graphics Inc.

SGML

Standard Generalized Markup Language

SHDSL

Single pair High bit-rate DSL

SI

Système Internationale d'unites [international unit system] ('affectionately' known as metrics)

SIC

Spelling [possibly] InCorrect

SID

Sound Interface Device

SIF

Statens Institut for Folkesundhed [Danish National Institute for People's Health]

SIG

Special Interest Group

SIGCHI

SIG on Computer-Human Interaction

SIIA

Software and Information Industry Association

SIMM

Single Inline Memory Module

SLA

Service Level Agreement

SLIP

Service Location Internet Protocol

SLP

Service Location Protocol

SMIL

Synchronized Multimedia Integration Language

SMOHT

;-) Secret Master Of Home Theater (one who is, or claims to be, privy to info the rest of us don't have) (from LP)

SMOKE

;-) Society for MOre Koal Energy (The Naked Gun 2 1/2)

SMS

Short Message Service

SMS

Systems Management Server (Microsoft)

SMTP

Simple Mail Transfer Protocol

SNA

Systems Network Architecture (IBM)

SNAFU

??? 

SNMP

Simple Network Management Protocol

SOB

Son Of a Bitch

SOFA

Southern Ontario Filemaker Association

SOHO

Small Office/Home Office

SOI

Silicon-On-Insulator

SOM

System Object Model (IBM)

SOP

Standard Operating Procedure

SPAB

Society for the Preservation of Ancient Buildings (UK)

SPEC

System Performance Evaluation Corp. (names a benchmark test)

SPECTRE

Special Executor for Counter-Intelligence, Terrorism, Revenge, and Extortion (James Bond)

SPILL

;-) Society of Petroleum Industry Leaders (L?) (The Naked Gun 2 1/2)

SPL

Sound Pressure Level

SQL

Structured Query Language

SR

Spectral Recording (as in Dolby SR)

SRI

Spectral Radius at Infinity

SRP

Suggested Retail Price

SS

Single Sided

SSA

Serial Storage Architecture

SSL

Secure Sockets Layer

SSLUG

Skåne Sjælland Linux User Group

ST

Sixteen/Thirty-two (as in Atari ST, referring to the Motorola 68000 CPU)

ST:DS9

Star Trek: Deep Space Nine

ST:TNG

Star Trek: The Next Generation

ST:TOS

Star Trek: The Original Series

STARS

Special Tactics And Rescue Squad (Resident Evil)

SUN

Stanford University Network

SUV

Sport/Utility Vehicle

SVGA

Super VGA (800x600 pixels)

SVJV

Så Vidt Jeg Ved [AFAIK]

SW

Star Wars

SWAP

Shared WAP

SWOT

Strengths/Weaknesses/Opportunities/Threats

SXGA

Super XGA (1280x1024 pixels)