Special Relativity Theory - the theory of relativity proposed by Albert Einstein

Sachin Tendulkar - a member of the Indian cricket team

Sex reassignment therapy - an umbrella term for all medical procedures regarding gender reassignment of both transgender and intersexual people

Scarborough RT - a public transport metro line in the Scarborough district of Toronto, Ontario, Canada

Sardinia Radio Telescope - a radio telescope under construction in Sardinia, Italy

Seattle Repertory Theatre - a Tony Award winning regional theatre located in Seattle, Washington

State Railway of Thailand - Thailand's state-owned railway operator

Sludge Retention Time - the time that sewage sludge is retained during treatment, see Sewage sludge treatment

Silver Ring Thing - a US-based sexual abstinence program

Special Rescue Team - elite SAR team of the Japanese Coast Guard

Single Rope Technique - a method used in caving and potholing to descend and ascend vertical drops

SubRip (.srt) - subtitle file format for video subtitles

Street and Racing Technology - Chrysler's SRT performance tuning engineering group which produces high performance vehicles

Special Reaction Teams - military equivalent of civilian SWAT

Singapore Repertory Theatre - a Singapore-based professional theatre group billed as one of the leading English language theatres in Asia

Standard Radio & Telefon AB - a Swedish computer manufacturer who developed an advanced mainframe as well as a computer terminal called Alfaskop

Souris River Telecommunications - a utility cooperative based in Minot, North Dakota

Super Robot Taisen - a video game and anime franchise also known as Super Robot Wars

Special Response Teams (SRT) - fictional combat units of the Mithril (organization) in the light novel and anime Full Metal Panic!

Shortest remaining time - a method of a CPU scheduling algorithm