1. an elongated lowland between ranges of mountains, hills, or other uplands, often having a river or stream running along the bottom.
2. an extensive area of land drained or irrigated by a river system.
3. A depression or hollow resembling or suggesting a valley, as the point at which the two slopes of a roof meet.

1. an elongated depression between hills or mountains, often with a river flowing through it.
2. the area which drains into a river.
3. any structure resembling one, e.g., the meeting point of two pitched roofs.
4. the internal angle formed by the intersection of two sloping roof planes.

1. the space inclosed between ranges of hills or mountains; the strip of land at the bottom of the depressions intersecting a country, including usually the bed of a stream, with frequently broad alluvial plains on one or both sides of the stream. also used figuratively.
2.
3. the place of meeting of two slopes of a roof, which have their plates running in different directions, and form on the plan a reëntrant angle.
4. the depression formed by the meeting of two slopes on a flat roof.

1. the depression between two ridges of a tooth, typically shown in such molars as those of the tapir and mastodon: correlated with lake, which is a depression surrounded by a raised ridge of enamel such as occurs in the molars of a horse.
2. A depression, or a relatively low and somewhat level area, more or less completely inclosed by hills or mountains; the basin of a stream of any size, or the area drained by it, and, in accordance with more general usage, the part of that area which lies near the stream and is not much raised above its level.
3. hence, any similar depression of any size.
4. specifically, in architecture, the internal angle formed by the meeting of two inclined sides of a roof.

1. a long depression in the surface of the land that usually contains a river