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.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.