The term slough (In the UK, pronounced to rhyme with cow; In the US, pronounced "slew") has several meanings related to wetland or aquatic features that seem to derive from local experience. For example:

• In the UK, a slough is a muddy or marshy area (for example see the probable derivation of Slough in Berkshire and other place names called Slough).
• In eastern and southeastern United States, a slough is a type of swamp or shallow lake system, typically formed as or by the backwater of a larger waterway. It is similar to a bayou with trees being present (that is, a swamp), and unlike a bog or marsh that lacks trees.
• In western U.S., a slough is a secondary channel of a river delta or a narrow channel in a shallow salt-water marsh, usually flushed by the tide. While this is in essence the same application of the term as used in the eastern U.S., a singular difference is that there exist no native trees in the west that would grow out into the waterway to form a swamp.
• In the northern Great Plains of the U.S. and Canada, a slough is a pond usually the result of glaciation; also called a pothole, whence prairie pothole region to describe the area where these sloughs are abundant.