What is "recessional hymn"

Recessional \Re*ces"sion*al\, a. Of or pertaining to recession or withdrawal.

Recessional hymn, a hymn sung in a procession returning from the choir to the robing room; a recessional.

A recessional hymn is a hymn placed at the end of a church service to close it. It is used commonly in the Catholic Church and Anglican Church, an equivalent to the concluding voluntary, which is called a Recessional Voluntary, for example a Wedding Recessional.