Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† birrus, i, m. (birrum, i, n., Aug. Serm. Divers. 49), = πυρρός (of yellow color), a cloak to keep off rain (made of silk or wool), Edict. Diocl. p. 20; cf. Salmas. Vop. Carin. 20; Burm. Anth. Lat. 2, p. 408; Cod. Th. 14, 10, 1, § 1; Schol. Juv. 8, 145; Sulp. Sev. Dial. 1, 21, 4; Claud. Epigr. 42.