meritless vs no-account

meritless is not a noun while no-account is a noun.

Word	Noun	Adjective	Verb	Adverb
meritless	No	Yes	No	No
no-account	Yes	Yes	No	No

As adjectives, meritless and no-account are synonyms defined as:

Other synonyms of meritless include good-for-naught, good-for-nothing, no-count, no-good, sorry.

meritless (noun)	no-account (noun)
	an idle worthless person

meritless (adjective)	no-account (adjective)
without merit; of little or no value or use	without merit; of little or no value or use