Pronunciation: (fôr, fōr),[key] —n. 1. a cardinal number, three plus one.
2. a symbol of this number, 4 or IV or IIII.
3. a set of this many persons or things.
4. a playing card, die face, or half of a domino face with four pips.
5. fours,Jazz.alternate four-bar passages, as played in sequence by different soloists: with guitar and piano trading fours. 6. Auto. a. an automobile powered by a four-cylinder engine.
b. the engine itself.
7. on all fours. See all fours (def. 3).