|1.||[ noun ] (geology) last 2 million years|
|Related terms:||period Cenozoic Pleistocene Holocene|
|2.||[ adjective ] (geology) 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"
|3.||[ adjective ] consisting of or especially arranged in sets of four|
"quaternate leaves" "a quaternary compound"
|4.||[ noun ] (mathematics) the cardinal number that is the sum of three and one|
|Synonyms:||four 4 quartet quatern tetrad quaternity quaternion quadruplet foursome Little_Joe IV|