n. [ L. capris goat + mulgere to milk. ] a widely distributed natural family of nocturnally active birds including the whip-poor-will (Caprimulgus vociferus), the chuck-will's-widow (Caprimulgus carolinensis), and the common nighthawk (Chordeiles minor); -- called popularly the goatsuckers or nightjars. The nighthawks are sometimes active during the day.
Syn. -- goatsuckers, nightjars, family Caprimulgidae. [ PJC ]

The family . . . is alternately known as the nightjars (derived from the "churring" sounds of several species -- "jarring" the night air), or goatsuckers, a nonsense name that should be discontinued as it has its origin in the preposterous myth that the birds sucked the milk of nanny goats until they were dry. Terence Michael Short (Wild Birds of the Americas)

n. an order of birds including the goatsuckers (Caprimulgidae), frogmouths, and the oilbird (guacharo) (family Steatornithidae).
Syn. -- order Caprimulgiformes. [ WordNet 1.5 ]