any nocturnal bird of the family Caprimulgidae, esp Caprimulgus europaeus (European nightjar): order Caprimulgiformes. They have a cryptic plumage and large eyes and feed on insects
Word origin
C17: night + jar2, so called from its discordant cry
nightjar in American English
(ˈnaɪtˌdʒɑr)
noun
any of a family (Caprimulgidae) of goatsuckers; esp., the common European nightjar(Caprimulgus europaeus)
Word origin
night + jar1: from the whirring noise made by the male