A circular or oval valley, or depression of the surface of the ground, the lowest part of which is generally occupied by a lake, or traversed by a river.

The entire tract of country drained by a river, or sloping towards a sea or lake.

An isolated or circumscribed formation, particularly where the strata dip inward, on all sides, toward a center; -- especially applied to the coal formations, called coal basins or coal fields.

A natural depression on the earth's surfaces, in which (usually water-borne) sediments accumulate over millions of years. The Gulf of Mexico is an example.

A hollow vessel or dish, to hold water for washing, and for various other uses.

A hollow place containing water, as a pond, a dock for ships, a little bay.

see sink.

A shallow sink.

Either an oceanic region with coherent features (e.g. the north Indian Ocean Basin), or a set of bathymetric data for use in numerical models.

See ocean basin.

A large, cup-shaped dent in the ocean floor.