Meaning

noun a composition of vocal music that is appropriate for opening church services

originPIE word *h₁én From Late Middle English introite (“act of entering in or into, entrance; place of entrance”), borrowed from Anglo-Norman introït, introïte (“introit”), or from its etymon Latin introitus (“act of entering in or into, entrance; passage; place of entrance; (figuratively) beginning, introduction, prelude”), from introeō (“to enter, go in”) + -tus (suffix forming action nouns from…

Etymology from Wiktionary, CC BY-SA 3.0