Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
somnĭfer, ĕra, ĕrum, adj. [somnus-fero], sleep-bringing, soporific, somniferous (poet. and in post-Aug. prose): vis papaveris, Plin. 18, 25, 61, § 229: virga (Mercurii), Ov. M. 1, 672: aspis, causing torpidity, deadly, Luc. 9, 701; so, venenum (aspidis), Ov. M. 9, 693: strychnos, App. Flor. 74; cf. somniculosus, II., and somnificus.