trough (trôf, trŏf)
a. A long, narrow, generally shallow receptacle for holding water or feed for animals.
b. Any of various similar containers for domestic or industrial use, such as kneading or washing.
2. A gutter under the edge of a roof for carrying off rainwater.
3. A long, narrow depression, as between waves or ridges.
4. A low point in a business cycle or on a statistical graph.
5. Meteorology An elongated region of relatively low atmospheric pressure, often associated with a front.
6. Physics A minimum point in a wave or an alternating signal.
[Middle English, from Old English trog; see deru- 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.