Slovak Republic

Suriname (ISO 3166-1 alpha-2 country code)

Sister, a nun's formal title.

Superman Returns, a 2006 film based on the iconic superhero

Shadowrun, a cyberpunk fantasy roleplaying game.

Serbian language (ISO 639 alpha-2)

Speech recognition, the process of converting speech to text.

Strontium, a chemical element of atomic number 38

School Rumble, an anime and manga series.

Sonic Rush, a video game

Southern Railway (UK)

Saudi riyal, the currency of Saudi Arabia.

Socialist-Revolutionary, as in Socialist-Revolutionary Party.

Nissan SR engine

Southern Railway (US)

Senior, added after a father's name when his son (suffixed "Jr.") has the same name.

scoville rating, a measure of the "hotness" of a chili pepper

Saarländischer Rundfunk, a German regional public broadcasting company.

Sveriges Radio, Sweden's national publicly-funded radio broadcasting company.

State Road, a road designation system in the U.S. state system

Socialist Republic, as in "SR Serbia", "SR Croatia", etc.

Systematic review standardized review

Selective repeat, a type of Automatic Repeat-reQuest Protocol.

Steradian, a unit of solid angle.

Seaman Recruit, the lowest enlisted rank in the U.S. Navy and Coast Guard

Strouhal number, a number used to describe oscillating flow mechanisms

SR programming language, a concurrent computer programming language

Sørvágs Róðrarfelag, a Faroese rowing association.

Sinus rhythm, the pattern made by a healthy heart on an electrocardiogram

Special relativity, a theory of space and time created by physicist Albert Einstein

Sustained release formulation of a medicine, e.g. Wellbutrin SR

Shift register, a group of processor registers set up in a linear fashion

Silk Road, a historically-significant interconnected series of caravan and ocean vessel trading routes across south-east Asia

Swissair (IATA code)

Simply Red, a pop/rock band

Skarloey Railway, a fictional railway in both The Railway Series and Thomas the Tank Engine and Friends by W.V. Awdry

Sonic Riders or Sonic R, both racing video games from the Sonic the Hedgehog series

Steve Rothery, the guitarist of Marillion

Spelling reform, demonstrably different from simplified spelling (particularly in the case of Hebrew).