The term 'Tetris Piece Shape' refers to the geometric shapes that appear in the classic video game Tetris. The most common shapes are the 'ELL', which is a three-letter acronym for the shape of a right angle with two connected lines extending from the corner. This shape is also known as an 'L-block' or an 'ELBOW'. Other shapes include the 'J-block', the 'S-block', the 'Z-block', the 'T-block', the 'O-block', and the 'I-block'. All of these shapes are used to create lines and rows in the game, and must be arranged strategically in order to clear lines and score points.