Late 15th century; earliest use found in Ludus Coventriae. After post-classical Latin agnus immaculatus (Vulgate: 1 Peter 1:19), itself after Hellenistic Greek ἀμνὸς ἄμωμος (New Testament).
Definition of immaculate lamb in US English:
immaculate lamb
noun
Used as an epithet of Christ.
Origin
Late 15th century; earliest use found in Ludus Coventriae. After post-classical Latin agnus immaculatus (Vulgate: 1 Peter 1:19), itself after Hellenistic Greek ἀμνὸς ἄμωμος (New Testament).