Open English Wordnet
Nouns
(n)four, 4, IV, tetrad, quatern, quaternion, quaternary, quaternity, quartet, quadruplet, foursome, Little Joethe cardinal number that is the sum of three and one
Adjectives
(s)quaternate, quaternaryconsisting of or especially arranged in sets of four“quaternate leaves”, “a quaternary compound”
(s)fourth, 4th, quaternarycoming next after the third and just before the fifth in position or time or degree or magnitude“the quaternary period of geologic time extends from the end of the tertiary period to the present”