1. (adj)four, 4, IV, tetrad, quatern, quaternion, quaternary, quaternity, quartet, quadruplet, foursome, Little Joe the cardinal number that is the sum of three and one Synonyms: quartette, quadruple, quaternion, quartet, quaternary, quad, tetrad, four, foursome, quaternity, intravenous feeding, quadruplet, quatern, four-spot Antonyms: ordinal
2. (adj)four, 4, iv being one more than three Synonyms: iv, four Antonyms: ordinal