any of numerous aquatic birds of the subfamily Sterninae of the family Laridae, related to the gulls but usually having a more slender body and bill, smaller feet, a long, deeply forked tail, and a more graceful flight, especially those of the genus Sterna, as S. hirundo(common tern) of Eurasia and America, having white, black, and gray plumage.
gull-like shore bird (subfamily Sterninae), 1678, via E.Anglian dialect, from a Scand. source (cf. Dan. terne, Swed. tärna, Færoese terna) related to O.N. þerna "tern," cognate with O.E. stearn "starling."