/ trɒf; NAmE trɔːf/ noun
1.
[ C ] a long narrow open container for animals to eat or drink from
2.
the trough [ sing. ] ( informal ) if you say that people have their noses in the trough , you mean that they are trying to get a lot of money for themselves
3.
[ C ] ( technical ) a long narrow region of low air pressure between two regions of higher pressure
—compare ridge
4.
[ C ] a period of time when the level of sth is low, especially a time when a business or the economy is not growing :
There have been peaks and troughs in the long-term trend of unemployment.
5.
[ C ] a low area between two waves in the sea, or two hills
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WORD ORIGIN
Old English trog , of Germanic origin; related to Dutch trog and German Trog , also to tree .