A long depression in the surface of the land that usually contains a river WordNet 3.0 & Open English WordNet

A valley is an elongated low area often running between hills or mountains, which will typically contain a river or stream running from one end to the other. Wikipedia

Low area between hills. Wikipedia Disambiguation

Low area between hills, often with a river running through it Wikidata

village in Fyodorovsky District, Russia Wikidata

Any low-lying land bordered by higher ground; especially an elongate, relatively large, gently sloping depression of the Earth's surface, commonly situated between two mountains or between ranges of hills or mountains, and often containing a stream with an outlet. OmegaWiki

An elongated depression between hills or mountains, often with a river flowing through it. Wiktionary

Elongated depression between hills or mountains. Wiktionary (translation)