drab vs gloomy

drab is a noun but gloomy is not a noun.

Word	Noun	Adjective	Verb	Adverb
drab	Yes	Yes	No	No
gloomy	No	Yes	No	No

As adjectives, drab and gloomy are synonyms defined as:

Other synonyms of drab include blue, dark, dingy, disconsolate, dismal, drear, dreary, grim, sorry.

drab (noun)	gloomy (noun)
a dull greyish to yellowish or light olive brown

drab (adjective)	gloomy (adjective)
of a light brownish green color	depressingly dark
lacking brightness or color; dull	filled with melancholy and despondency
causing dejection	causing dejection
lacking in liveliness or charm or surprise