an elongated depression between uplands, hills, or mountains, esp. one following the course of a stream.

an extensive, more or less flat, and relatively low region drained by a great river system.

any depression or hollow resembling a valley.

a low point or interval in any process, representation, or situation.

any place, period, or situation that is filled with fear, gloom, foreboding, or the like

the valley of despair.

Architecture . a depression or angle formed by the meeting of two inclined sides of a roof.

the lower phase of a horizontal wave motion.

noun

basin , bottom , canyon , channel , coulee , dale , dell , depression , dingle , glen , gorge , lowland , notch , plain , swale , trough , vale , chasm , cirque , clough , combe , cove , divide , gulch , gully , hollow , ravine , rill , strath