TR

TR or tr may stand for many things.

In official codes:
* Tiger Airways IATA code (since September 2003)
* Tomahawk Railway, AAR reporting marks TR
* Transbrasil airline IATA code (to 2001)
* Turkey, the ISO 3166-1 alpha-2 country code
* Turkish language, in ISO 639 alpha-2
* The postal code for the Truro area covering West Cornwall

In history:
* Textus Receptus
* Theodore Roosevelt, 26th President of the United States
** The "USS Theodore Roosevelt (CVN-71)", a Nimitz-class aircraft carrier

In computing and science:
* the table row HTML element
* tr, a Unix program
* trace (linear algebra), the sum of the main diagonal elements of a square matrix in linear algebra
* The digraph tr
* Transistor
* Texas Red fluorescent dye
* Tons of Refrigeration in Ton#Refrigeration_ton
* Technical report
* Technical review

In medicine:
* Tubal reversal, microsurgery to open and reconnect the fallopian tubes after a tubal ligation procedure

In music:
* The Rasmus
* Terminaator, an Estonian band, has shortened its name as TR
* Trill
* TR-909; TR-808 etc. drum machines made by Roland in the 1980s

In games:
* Tomb Raider, computer video game series
* Tabula Rasa (computer game), the MMO game made by NCsoft
* TalesRunner, the online game
* Terran Republic in the MMOFPS computer video game "PlanetSide"
* True Remembrance, a freeware visual novel

In transportation:
* Talyllyn Railway the world's first preserved heritage railway - Wales, UK
* Triumph Motor Company
* Thai Rung Union Car
* Toll Rail division of Toll NZ
* Tranz Rail

In sports:
* Toronto Raptors

In fashion:
* True Religion, a designer denim company that is often referred to by its initials, TR

In other uses:
* Thematic Group Resources (a deprecated title for a group of properties in the National Register of Historic Places)
* The Replacements, a children's television show on the Disney Channel
* Training Routines, in Scientology
* Team Rocket
* Trent Reznor