a state of dejection, hopelessness, or degradation

a slough of self-pity

the cast-off skin of a snake

a mass of dead tissue separating from a wound, an ulcer, etc

to cast off (e.g. a skin or shell)

(+ off) to get rid of or discard (something) as irksome or objectionable

said e.g. of a skin: to become shed or cast off

said e.g. of a snake: to cast off a skin