Tetrominoes

Part of speech: noun

Definitions

1. A set of four connected squares arranged in various forms, often used in games and puzzles
2. Shapes composed of four squares connected edge-to-edge, frequently appearing in Tetris-like games
3. Geometric figures made up of four unit squares linked together, commonly utilized in recreational mathematics and gaming contexts

Etymology: "Tetrominoes" is the plural of "tetromino," a compound built from the Greek prefix "tetra-," meaning four, joined to "-omino," a suffix borrowed from "domino." The shape is named after the number of squares it contains, so the family is defined by count rather than by any particular arrangement. The "-omino" ending is the surprising part. It comes from "domino," the game piece, and the shapes take their name from the pattern that the older word established. Mathematicians first grouped squares into polyominoes in this way, with "domino" meaning two squares, "tromino" three, and "tetromino" four, so each new term simply swaps the number prefix onto the same stem. The Greek root "tetra-" ultimately traces back to a word for "four," which appears in many English scientific terms such as "tetrahedron." Because the prefix is ancient but the combined puzzle-shape vocabulary is modern, the word belongs to the recreational mathematics tradition rather than to classical usage.