a. Of or pertaining to recession or withdrawal. [ 1913 Webster ]
Recessional hymn, a hymn sung in a procession returning from the choir to the robing room; a recessional. [ 1913 Webster ]
n. a hymn or other piece of music sung or played while a church congregation is leaving a service, or a choir is returning to the cloak room; a recessional hymn. [ PJC ]