What is the meaning of Introit?

A prayer, typically part of a psalm or other portion of the Bible, read or sung at the start of Mass while or immediately after the priest ascends to the altar.

Any piece of vocal music, especially a setting of an anthem or a psalm, sung at the opening of a church service.

The action of entering or going in; an entrance.

An introduction.

third-person singular present active indicative of introeĊ

introit, introitus (part of a psalm or other portion of the Bible read or sung at Mass immediately after the priest ascends to the altar)

Source: wiktionary.org