ichthyornisEnglishOxford New American Dictionaryichthyornis /ˌikTHēˈôrnis, ˌɪkθiˈɔrnɪs / ▸ noun an extinct, gull-like, fish-eating bird of the late Cretaceous period, with large toothed jaws. Genus Ichthyornis, order Ichthyornithiformes. – ORIGIN modern Latin, from ichthyo- + Greek ornis ‘bird’.