clough

noun

1.
a long narrow depression in a surface
geo chap crack cranny crevice fissure
2.
conduit that carries a rapid flow of water controlled by a sluicegate
penstock sluice sluiceway
3.
the trees and other plants in a large densely wooded area
lum forest wood woods
4.
the region of the angle formed by the junction of two branches
crotch fork