Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
cervīcōsus, a, um, adj. [cervix], stubborn, obstinate, Eccl. Ambros. ap. Voss. Vit. L. L. 3, 4; cf.: cervicosus αὐχενίας, Gloss. Labb.