dingy vs drab

dingy is not a noun while drab is a noun.

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

As adjectives, dingy and drab are synonyms defined as:

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

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

dingy (adjective)	drab (adjective)
causing dejection	of a light brownish green color
thickly covered with ingrained dirt or soot	lacking brightness or color; dull
(of color) discolored by impurities; not bright and clear	causing dejection
	lacking in liveliness or charm or surprise