Main Entry: ¹ter·tia·ry

Pronunciation: \ˈtər-shē-ˌer-ē, -shə-rē\

Function: noun

Inflected Form(s): plural ter·tia·ries

Date: circa 1550

1 [Medieval Latin tertiarius, from Latin, of a third] : a member of a monastic third order especially of lay people
2 capitalized : the Tertiary period or system of rocks