Any of about 40 species (subfamily Sterninae, family Laridae) of slender, web-footed, migratory water birds found almost worldwide.
Species vary from 8 to 22 in. (20–55 cm) long. The plumage is white, black-and-white, or black; the sharply pointed bill is black, red, or yellow; and the feet are red or black. Most species have long, pointed wings and a forked tail. Terns plunge into the water to catch crustaceans and fishes. They breed colonially, usually on the ground on islands. See also Arctic tern .