Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
ŏb-uncus, a, um, adj., bent in, hooked (poet.): rostroque immanis vultur obunco, Verg. A. 6, 597: pedes, Ov. M. 6, 516: falx, Arn. 6, 197.