tertiaries definition
tertiaries. 1  1 [Medieval Latin tertiarius, from Latin, of a third] : a member of a monastic third order especially of lay people. 2  2 capitalized : the Tertiary (see 2tertiary) period or system of rocks.
Definition of tertiary. plural. tertiaries. 1 [Medieval Latin tertiarius, from Latin, of a third] : a member of a monastic third order especially of lay people. 2 capitalized : the Tertiary (see 2tertiary) period or system of rocks.