TR or tr may stand for:

In official codes:

  • Tiger Airways IATA code (since September 2003)
  • Tomahawk Railway
  • Transbrasil airline IATA code (to 2001)
  • Turkey, the ISO 3166-1 alpha-2 country code
    • .tr, the country code top level domain (ccTLD) for Turkey
  • Turkish language, in ISO 639 alpha-2
  • TR postcode area, the postal code for the Truro area covering West Cornwall
  • Tactical Reconnaissance, a code used for the Lockheed U-2

In history:

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

In engineering, science and computing:

  • 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
  • Technical report
  • Technical review
  • the Thyroid hormone receptor is a type of nuclear receptor that is activated by binding thyroid hormone
  • an abbreviation for the trityl (triphenylmethane) group in chemistry
  • Matrix trace

In medicine:

  • Tubal reversal, a microsurgery to open and reconnect the fallopian tubes after a tubal ligation procedure
  • Tricuspid regurgitation, a leakage of blood within the heart

In music:

  • The Rasmus
  • The Resistance, the fifth studio album by the British band Muse
  • Terminaator, an Estonian band, has shortened its name as TR
  • Trill
  • TR-909; TR-808 etc., a series of drum machines made by Roland in the 1980s
  • Korg TR, a music workstation synthesizer

In games:

  • Tomb Raider, a computer video game series
  • Tabula Rasa (computer game), the MMO game made by NCsoft
  • TalesRunner, an online game
  • Terran Republic, a term used in the MMOFPS computer video game PlanetSide
  • True Remembrance, a freeware visual novel

In transportation:

  • Talyllyn Railway, the world's first preserved heritage railway in Wales, United Kingdom
  • Triumph Motor Company
  • Thai Rung Union Car
  • Toll Rail division of Toll NZ
  • Tranz Rail
  • NZR TR class rail engines
  • Toronto Rocket (Toronto subway car), an articulted subway car for the Toronto subway system

In sports:

  • Texas Rangers (baseball)
  • Toronto Raptors

In fashion:

  • True Religion, a designer denim company that is often referred to by its initials, TR

In places:

  • Toms River, New Jersey
  • Travelers Rest, South Carolina, a town in Upstate Greenville County, South Carolina, United States

In other uses:

  • Thematic Group Resources, a deprecated title for a group of properties in the National Register of Historic Places
  • The Replacements (TV series), a children's television show on the Disney Channel
  • Training routines (Scientology), a term used in Scientology
  • Team Rocket (Pok√©mon)
  • Trent Reznor
  • Trip report
  • Vijaya T. Rajendar