Trough

1. A long, hollow vessel, generally for holding water or other liquid, especially one formed by excavating a log longitudinally on one side; a long tray; also, a wooden channel for conveying water, as to a mill wheel.
2. Any channel, receptacle, or depression, of a long and narrow shape; as, trough between two ridges, etc.
3. (Meteor.) The transverse section of a cyclonic area where the barometric pressure, neither rising nor falling, has reached its lowest point.
Trough gutter (Arch.),
a rectangular or V-shaped gutter, usually hung below the eaves of a house.
Trough of the sea ,
the depression between two waves.