(UK, regional) A nightjar, especially . from 17th c.
(US) A New World nightjar of the genus Chordeiles, especially . from 18th c.
1929, Ernest Hemingway, A Farewell to Arms, Folio Society 2008, p. 91:The swallows circled around and I watched them and the night-hawks flying above the roofs and drank the Cinzano.
A person whose preference or custom is to remain awake and active during the night and the early morning hours. from 19th c.
