(Part of the) common name of most species of the subfamily Sterninae of the family Laridae (Charadriiformes, suborder Lari) and in the plural the general term for the subfamily. Terns are in many ways like gulls (also listed), but on the average they are smaller and more slender birds, with long, narrow and pointed wings and often with (deeply) forked tails; therefore another popular name is 'sea-swallows'. Most species have a sexual monomorphic, white plumage with grey backs and wings, and with a dark crown at least in the breeding season. The pointed bill is often directed downwards in flight and the feet are webbed, although most of the species seldom swim. Terns feed on fish and other marine animals which are characteristically caught by plunging from a height. They are very gregarious (flock-forming) and often breed in colonies of large size, where most species breed on the ground. The largest number of species occur in the Pacific Ocean, but they have a world-wide distribution, mostly inhabiting the coasts.

Alternative forms for terns : Chlidonias, Gelochelidon, Sterna, tern.