A triomino, also known as a tromino, is a 3-polyomino. There are two free polyominoes, (the same) two one-sided polyominoes, and 6 fixed
polyominoes. The free polyominoes are known as the L-triomino
(or right triomino) and straight triomino,
respectively.
There is also a game called triomino consisting of 55 equilateral triangles, each containing three numbers from 0 to 5 at each vertex. Every combination of tiles is in the game, although those tiles with three different values are allowed to be arranged only in clockwise-increasing order.
