—adj.
1 having four parts.
2 (Quaternary) Geol. of or relating to the most recent period in the Cenozoic era with evidence of many species of present-day plants and animals (cf. PLEISTOCENE, HOLOCENE).
Usage:
Cf. Appendix II.
—n. (pl. -ies)
1 a set of four things.
2 (Quaternary) Geol. the Quaternary period or system.
Etymology: ME f. L quaternarius f. quaterni distrib. of quattuor four
Useful english dictionary. 2012.