drab vs sober

drab is a noun but sober is not a noun.

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

As adjectives, drab and sober are synonyms defined as:

Other synonyms of drab include somber, sombre.

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

drab (adjective)	sober (adjective)
of a light brownish green color	not affected by a chemical substance (especially alcohol)
lacking brightness or color; dull	completely lacking in playfulness
causing dejection	lacking brightness or color; dull
lacking in liveliness or charm or surprise	dignified and somber in manner or character and committed to keeping promises

drab (verb)	sober (verb)
	become sober after excessive alcohol consumption
	become more realistic
	cause to become sober