nightjar (n.)youdaoicibaDictYouDict[nightjar 词源字典]
nocturnal bird, goatsucker, 1620s, from night + jar (v.). So called for the "jarring" sounds made by the male when the female is brooding, which have been described as a "churring trill that seems to change direction as it rises and falls." An Old English word for it was nihthræfn "night raven."[nightjar etymology, nightjar origin, 英语词源]