trough

(trôf, trŏf)

1. 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 eaves of a roof.
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.