depressed vs down

depressed is not a noun while down is a noun.

Word	Noun	Adjective	Verb	Adverb
depressed	No	Yes	No	No
down	Yes	Yes	Yes	Yes

As adjectives, depressed and down are synonyms defined as:

Other synonyms of depressed include blue, dispirited, down in the mouth, downcast, downhearted, gloomy, grim, low-spirited, low.

As adjectives, depressed and down are synonyms defined as:

depressed (noun)	down (noun)
	(American football) a complete play to advance the football
	soft fine feathers
	fine soft dense hair (as the fine short hair of cattle or deer or the wool of sheep or the undercoat of certain dogs)
	(usually plural) a rolling treeless highland with little soil

depressed (adjective)	down (adjective)
filled with melancholy and despondency	being or moving lower in position or less in some value
lower than previously	filled with melancholy and despondency
flattened downward as if pressed from above or flattened along the dorsal and ventral surfaces	extending or moving from a higher to a lower place
	becoming progressively lower
	not functioning (temporarily or permanently)
	lower than previously
	shut
	being put out in a game of baseball
	understood perfectly

depressed (verb)	down (verb)
	improve or perfect by pruning or polishing
	bring down or defeat (an opponent)
	drink down entirely
	eat up completely, as with great appetite
	cause to come or go down
	shoot at and force to come down

depressed (adverb)	down (adverb)
	spatially or metaphorically from a higher to a lower level or position
	away from a more central or a more northerly place
	paid in cash at time of purchase
	in an inactive or inoperative state
	to a lower intensity
	from an earlier time