TOS

TOS may refer to:

General

 * Terms of service
 * The original series of a particular media, in contrast to a spin-off

Chemistry

 * Tosyl, a chemical group
 * Gy's sampling theory (abbreviation)

Entertainment

 * Star Trek: The Original Series, a science fiction TV series originally known as Star Trek
 * Tree of Savior, a multiplayer online role playing game published by IMC Games in 2016
 * Town of Salem, a social deduction game published by BlankMediaGames in 2014
 * Temple of Shadows, 2004 album by Angra
 * T·O·S (Terminate on Sight), 2008 album by G-Unit

Medicine

 * Thoracic outlet syndrome, a medical condition
 * Toxic oil syndrome, caused by consuming non-food grade oil

Organizations

 * The Oceanography Society
 * Theosophical Order of Service, an international organization
 * Temple of Set, an occult society
 * Tennessee Ornithological Society
 * Trucial Oman Scouts, UK force raised in Oman in 1951
 * TV Oita, a Japanese TV station

Other uses

 * TOS-1, a Soviet thermobaric weapon
 * Tam o' Shanter (cap)
 * Atari TOS (The Operating System, also unofficially known as Tramiel Operating System), computer operating system
 * TOS/360, Tape Operating System/360
 * Tromsø Airport, Norway, IATA code
 * Type of service, a field in the header of IPv4 packets
 * Terminal Operating System, controlling cargo movement
 * Testament of Solomon, a pseudepigraphical composite text ascribed to King Solomon
 * Thinkorswim, an electronic trading platform by TD Ameritrade used to trade financial assets
 * Town of Salem, a game under the social deduction genre