loon (n.1)youdaoicibaDictYouDict[loon 词源字典]
large diving bird (especially the Great Northern Diver), 1630s, from a Scandinavian source (compare Norwegian lom, from Old Norse lomr).[loon etymology, loon origin, 英语词源]
loon (n.2)youdaoicibaDictYouDict
"crazy person," mid-15c., lowen "rascal," of uncertain origin, perhaps related to Dutch loen "stupid person."