TETRIS GLOSSARY
O piece
Also called O tetromino · Square piece
The two-by-two square. Its outline stays the same when rotated.
View in the A–Z glossary →SPAWN ORIENTATION
Four cells in a square. Its outline stays the same when rotated.
Related terms
Tetromino →
A shape made from four edge-connected squares. Tetris uses seven one-sided shapes: I, J, L, O, S, T and Z. Letter names avoid confusion when different games use different colors.
Rotation state →
The current orientation of a piece. SRS labels states 0, R, 2 and L. Even pieces with repeated outlines can occupy different cells within their rotation box.