Anous= (trisyllable), without understanding , foolish.
Bill, tip decurved. Nostrils in groove, further from base of bill than in Sterna. Tail cuneate. Fourth feather from outside longest (third in Micranous). Feet large. Toes fully webbed. Plumage dark. Tropical oceanic birds allied to Terns, but with a slower and heavier flight and very different habits. Live in the open sea and settle on the water to feed. Tropical and subtropical seas. The only Tern's eggs laid in a nest.