mooneye Syllabification: (moon·eye)Pronunciation: /ˈmo͞onˌī/Definition of mooneye noun a herringlike freshwater fish with large eyes, found exclusively in central and eastern North America. Genus Hiodon, family Hiodontidae: two species, the goldeye (H. alosoides) and the larger-eyed mooneye (H. tergisus)