nighthawkPronunciation: /ˈnʌɪthɔːk/Definition of nighthawk noun 1an American nightjar with sharply pointed wings. Family Caprimulgidae: four genera and several species, in particular the common nighthawk (Chordeiles minor) of North America 2North American term for night owl.nighthawk in other Oxford dictionaries Definition of nighthawk in the US English dictionary