The Collaborative International Dictionary of English v.0.48:

Agnus \Ag"nus\, n.; pl. E. Agnuses; L. Agni. [L., a lamb.]
   Agnus Dei.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Agni
    n 1: (Sanskrit) Hindu god of fire in ancient and traditional
         India; one of the three chief deities of the Vedas