The term 'Tetris Shapes' refers to the seven distinct shapes that appear in the classic video game Tetris. These shapes, known as tetrominoes, consist of four squares arranged in various configurations. The seven shapes are an I-shape, an O-shape, a T-shape, a J-shape, an L-shape, a S-shape, and a Z-shape. The term 'ELLS' is an acronym for these seven shapes, with each letter representing one of the shapes.