Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† ŏnŏchīles, is, and ŏnŏchēlis, is, f., and ŏnŏchīlon, = ὀνοχειλές, ὀνοχειλίς, a plant, a kind of bugloss, Plin. 22, 21, 25, § 51.