奶牛

[ noun ]
domesticated bovine animals as a group regardless of sex or age
<noun.animal>
so many head of cattlewait till the cows come home
seven thin and ill-favored kine
a team of oxen

Cow \Cow\, n.; pl. {Cows} (kouz); old pl. {Kine} (k[imac]n).
[OE. cu, cou, AS. c[=u]; akin to D. koe, G. kuh, OHG. kuo,
Icel. k[=y]r, Dan. & Sw. ko, L. bos ox, cow, Gr. boy^s, Skr.
g[=o]. [root]223. Cf. {Beef}, {Bovine}, {Bucolic}, {Butter},
{Nylghau}.]
1. The mature female of bovine animals.

2. The female of certain large mammals, as whales, seals,
etc.

cows \cows\ n. pl. [pl. of cow.]
domesticated bovine animals as a group regardless of sex or
age; as, wait till the cows come home.

Syn: cattle, kine, oxen, Bos taurus.
[WordNet 1.5]