Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
agnus, i, m. (gen. plur. agnūm, Porc. Licin. ap. Gell. 19, 9, 13) [cf. ἀμνός, which Benfey connects with ὄϊς = Sanscr. avis; Lith. ávinas = sheep], a lamb, usually for sacrifice: TERTIA. SPOLIA. IANO. QVIRINO. AGNOM. MAREM. CAEDITO, from an ancient law (of Numa?), in Fest. s. v. opima, p. 190: IVNONI. CRINIBVS. DEMISSIS. AGNAM. FEMINAM. CAEDITO., from a law of Numa in Gell. 4, 33, and Fest. s. v. pellices, p. 121: jam ego te hic agnum faciam et medium distruncabo, Plaut. Truc. 2, 7, 54; Varr. R. R. 2, 2, 4 al.: agnus absque maculā, Vulg. Exod. 12, 5: agnos immaculatos, ib. Lev. 14, 10: villa abundat porco, haedo, agno, Cic. Sen. 16, 56; id. Div. 2, 11, 39; Ov. M. 7, 320; Hor. C. 3, 18, 13: ara avet immolato Spargier agno, id. ib. 4, 11, 8 al.
Prov.: Agnum lupo eripere velle, to wish to rescue a lamb from a wolf, i. e. to wish what is impossible, Plaut. Poen. 3, 5, 31.
Eccl. Lat., of Christ: quasi agni immaculati Christi, Vulg. 1 Pet. 1, 19: Ecce Agnus Dei, ib. Joan. 1, 29: ceciderunt coram Agno, ib. Apoc. 5, 8 al.