invertedT

An invertedT is the geometric figure formed by a horizontal bar with a centered stem extending in the downward direction, i.e., a T shape rotated 180 degrees. It is visually the same T silhouette but flipped so the crossbar sits at the bottom and the stem points downward. In many tiling and puzzle contexts, invertedT refers to this rotated form and to its appearances as small polyforms.

In tiling theory and puzzle games, the invertedT occurs as a tetromino (four-square) or pentomino (five-square) shape; it is one of the rotations of the T piece used in games such as Tetris. The shape is symmetric with respect to a vertical axis, but not with respect to a horizontal axis.

In civil engineering and road design, the term invertedT is used descriptively for an inverted-T intersection, a junction in which one road meets another at a T-shaped configuration with the longer road continuing past the intersection in the opposite direction relative to the side branch. The orientation can be reversed by rotating the plan view; traffic patterns, right-of-way rules, and signaling differ from standard T-intersections.

See also: T-tetromino, T-pentomino, T-intersection, polyomino, geometry.