Noun

1. A part of the mass beginning with the words "Agnus Dei", or the music to which it is set.
2. A small model of a lamb with a cross.
3. A bar of wax imprinted with a similar shape and blessed by the Pope.
   • 1796, Matthew Lewis, The Monk, Folio Society 1985, p. 194:

     Matilda continued her incantations; at intervals she took various items from the basket, the nature and name of most of whichwere unknown to the friar: but among the few which he distinguished, he particularly observed three human fingers, and an agnus dei, which she broke in pieces.

Noun

1. Literally, "Lamb of God"
2. title applied to Jesus Christ, as Son of God the Father and someone willing to sacrifice himself
3. prayer in the Mass, and musical composition of that prayer, which begins with the words "Agnus Dei...."

   Agnus Dei, qui tollis peccata mundi...

   Lamb of God, who take away the sins of the world...