What is "trough gutter"

Trough \Trough\ (tr[o^]f), n. [OE. trough, trogh, AS. trog, troh; akin to D., G., & Icel. trog, Sw. tr[*a]g, Dan. trug; probably originally meaning, made of wood, and akin to E. tree. [root]63 & 24

1. See Tree, and cf. Trug.] 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.