tern (n.)youdaoicibaDictYouDict[tern 词源字典]
gull-like shore bird (subfamily Sterninae), 1670s, via East Anglian dialect, from a Scandinavian source (compare Danish terne, Swedish tärna, Færoese terna) related to Old Norse þerna "tern" (also "maid-servant"), cognate with Old English stearn.[tern etymology, tern origin, 英语词源]