Meaning of TROUGH in English
n.1 a long narrow open receptacle for water, animal feed, etc.
2 a channel for conveying a liquid.
3 an elongated region of low barometric pressure.
4 a hollow between two wave crests.
5 the time of lowest economic performance etc.
6 a region around the minimum on a curve of variation of a quantity.
7 a low point or depression.
Etymology: OE trog f. Gmc
Oxford English vocab. Оксфордский английский словарь. 2012