ud·der / ˈədər/ • n. the mammary gland of female cattle, sheep, goats, horses, and related ungulates, a baglike organ with two or more teats hanging near the hind legs.DERIVATIVES: ud·dered adj. [in comb.] .

udder OE. ūder = OS. ūder, MLG., MDu. ūder (Du. ui(j)er), OHG. ūter (G. euter):- WGmc. *ūdr-; cf. OS. ieder, MLG. jeder, jüdder, ON. (with unexpl. cons. -change) jú (g)r :- *euðer; IE. *ūdhr- is repr. by L. ūber, Gr. oûthar, Skr. ū́dhar-.