[trough] n, pl troughs [ME, fr. OE trog; akin to OHG trog trough, OE treow tree, wood--more at tree] (bef. 12c) 1 a: a long shallow often V-shaped receptacle for the drinking water or feed of domestic animals b: any of various domestic or industrial containers
2. a: a conduit, drain, or channel for water; esp: a gutter along the eaves of a building b: a long and narrow or shallow channel or depression (as between waves or hills); esp: a long but shallow depression in the bed of the sea--compare trench
3: the minimum point of a complete cycle of a periodic function: as a: an elongated area of low barometric pressure b: the low point in a business cycle