Tri may refer to:
- An intern specializing in Float and Share research.
- tri-, a numerical prefix meaning three
- El Tri or El Tricolor, are the nickname of the Mexico national football team.
- El Tri, Mexican rock group
- Tri (card game), two or three-player matching card game
- Tri (novel), a Slovenian novel
- Tri (Ana Stanić album)
- Transport Research Institute, in Scotland
- Triangular function, tri(t)
- Tri-Cities Regional Airport which uses IATA code TRI
- Triangulum, a constellation (standard astronomical abbreviation)
- Toxics Release Inventory, a program to report the amount of toxic wastes in the United States
- Tri (Tibetan Buddhism) instructions on how practice tantra in Tibetan Buddhism