TR

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