How do you spell Trough

Available Definitions:
1) n. - 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) n. - Any channel, receptacle, or depression, of a long and narrow shape; as, trough between two ridges, etc.