From Middle English udder, uddyr (also as uther, iddyr), from Old English ūder (“udder; breast”), from Proto-Germanic *ūdarą, from Proto-Indo-European *h₁ówHdʰr̥ (“udder”). Cognate with Saterland Frisian Jadder (“udder”), Dutch uier (“udder”), German Euter (“udder”), Swedish juver (“udder”), Icelandic júgur (“udder”), Vedic Sanskrit ऊधर् (ū́dhar), Ancient Greek οὖθαρ (oûthar), Latin ūber.