What does slough mean?

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slough

Pronunciation: (slou for 1, 2, 4; slOO for 3), [key]
n.
1. an area of soft, muddy ground; swamp or swamplike region.
2. a hole full of mire, as in a road.
3. Also,slew,slue. Northern U.S. and Canadian. a marshy or reedy pool, pond, inlet, backwater, or the like.
4. a condition of degradation, despair, or helplessness.

slough

Pronunciation: (sluf), [key]
n.
1. the outer layer of the skin of a snake, which is cast off periodically.
2. Pathol.a mass or layer of dead tissue separated from the surrounding or underlying tissue.
3. anything that is shed or cast off.
4. Cards.a discard.

v.i.
1. to be or become shed or cast off, as the slough of a snake.
2. to cast off a slough.
3. Pathol.to separate from the sound flesh, as a slough.
4. Cards.to discard a card or cards.

v.t.
1. to dispose or get rid of; cast (often fol. by off): to slough off a bad habit.
2. to shed as or like a slough.
3. Cards.to discard (cards).
4. slough over,to treat as slight or trivial: to slough over a friend's mistake. Also,sluff.