adj. & n.
--adj.
1. third in order or rank etc.
2 (Tertiary) Geol. of or relating to the first period in the Cenozoic era with evidence of the development of mammals and flowering plants (cf. PALAEOCENE, EOCENE, OLIGOCENE, MIOCENE, PLIOCENE).
Usage:
Cf. Appendix II.
--n.
1. Geol. this period or system.
2 a member of the third order of a monastic body.
Phrases and idioms:
tertiary education education, esp. in a college or university, that follows secondary education.
Etymology: L tertiarius f. tertius third