General terms:
* Dale: A broad, shallow valley, often used in poetic or literary contexts.
* Hollow: A small, enclosed valley, often with a stream or river running through it.
* Gorge: A deep, narrow valley with steep sides, often carved by a river.
* Canyon: A deep, narrow valley with steep sides, often carved by a river, especially in arid regions.
* Ravine: A small, narrow gorge, often with steep sides.
* Depression: A low-lying area of land, often used in a more general sense to describe any area that is lower than the surrounding land.
* Basin: A large, bowl-shaped depression, often used to describe a valley surrounded by mountains.
* Vale: A synonym for "valley," often used in poetic or literary contexts.
More specific terms:
* Glacial valley: A valley formed by the erosion of glaciers.
* River valley: A valley formed by the erosion of a river.
* Dry valley: A valley that is no longer actively eroded by a river or glacier.
* Intermontane valley: A valley located between mountains.
* U-shaped valley: A valley shaped like a U, formed by the erosion of glaciers.
* V-shaped valley: A valley shaped like a V, formed by the erosion of rivers.
The best word to use will depend on the specific context and the characteristics of the valley you are referring to.