cow 1 (kou)
1. The mature female of cattle of the genus Bos.
2. The mature female of certain other large animals, such as elephants, moose, or whales.
3. A domesticated bovine of either sex or any age.
have a cow
Slang To become amazed, angered, or upset: He had a cow when he saw the mess we made.
till the cows come home Informal
For a very long time; indefinitely: They could argue till the cows come home and still not reach an agreement.
[Middle English cou, from Old English cū; see gwou- in the Appendix of Indo-European roots.]
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