peripheral vs marginal

peripheral is a noun but marginal is not a noun.

Word	Noun	Adjective	Verb	Adverb
peripheral	Yes	Yes	No	No
marginal	No	Yes	No	No

peripheral (noun)	marginal (noun)
electronic equipment external to the circuit board that contains the CPU of a computer

peripheral (adjective)	marginal (adjective)
on or near an edge or constituting an outer boundary; the outer area	of questionable or minimal quality
related to the key issue but not of central importance	just barely adequate or within a lower limit
	at or constituting a border or edge
	producing at a rate that barely covers production costs