introit
/ɪnˈtroʊ.ɪt/Definitions
1. noun
The opening song or hymn sung when a priest enters the church at the beginning of a Mass or other service.
“The choir performed a beautiful introit during the morning Mass.”
2. verb
To introduce or bring in something, especially a musical or liturgical element.
“The new priest will introit a new hymn in the Sunday service.”