Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
mūgil and mūgĭlis, is, m., a sea-fish; acc. to some, the mullet: mugilum natura ridetur, in metu capite abscondito, totos se occultari credentium, Plin. 9, 17, 26, § 59; 9, 42, 67, § 144; 9, 62, 88, § 185; 10, 70, 89, § 193; 32, 11, 53, § 149.
This fish was made use of in punishing adulterers: quosdam moechos et mugilis intrat, Juv. 10, 317; cf. Cat. 15, 19.