quaternary
adjective
1. consisting of or especially arranged in sets of four
- quaternate leaves
- a quaternary compound
Similar word(s): multiple, quaternate
2. coming 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
noun
1. last 2 million years
Definition categories: time
2. the cardinal number that is the sum of three and one
Similar word(s): four, foursome, quadruplet, quartet, quaternion, quaternity, tetrad