antifonario 31
1º_ In the Catholic liturgy, the book that gathers the antiphons to sing all year round is called antiphon or antiphonary. See suffix -aryan . 2º_ Although it is of very old use, it used to be called that in the Spain of the sixteenth century to the ass, to the buttocks. There is not much certainty about the origin of this version, some theories associate it with the fact that the antiphon is a dialogue between two choirs, and the book contains both songs (which in one of its meanings means "buttocks"); in others the custom of singing it standing is remembered, but in the face of fatigue the religious were always discovered supporting the buttocks on any protrusion of walls or furniture, although this explanation seems even less plausible than the previous one.