What does "slough" mean?

Additional senses

1. 2.[Pronounced sloo.] A wet place; a swale; a side channel or inlet from a river. Note: [In this sense local or provincial; also spelt sloo, and slue.] Slough grass (Bot.), a name in the Mississippi valley for grasses of the genus Muhlenbergia; -- called also drop seed, and nimble Will.
2. 3.imp. of Slee, to slay. Slew. Chaucer.
3. 4.The skin, commonly the cast-off skin, of a serpent or of some similar animal.
4. 5.(Med.) The dead mass separating from a foul sore; the dead part which separates from the living tissue in mortification.
5. 6.To form a slough; to separate in the form of dead matter from the living tissues; -- often used with off, or away; as, a sloughing ulcer; the dead tissues slough off slowly.
6. 7.To cast off; to discard as refuse. New tint the plumage of the birds, And slough decay from grazing herds. Emerson.