Medium-sized tern. Long, slender yellow to reddish orange bill, appears to droop at tip. Short, forked tail. Complete black cap while breeding. Black in narrow, shaggy band around back of head; forehead white in winter. Mostly white all over, with some dark in wingtips. Underparts often with pink blush.
Juvenile similar to nonbreeding adult, but bill smaller and pale yellow to orange-red, back with variable amounts of dark spotting, and wingtips darker.