fairly vs middling

fairly is not a noun while middling is a noun.

Word	Noun	Adjective	Verb	Adverb
fairly	No	No	No	Yes
middling	Yes	Yes	No	Yes

As adverbs, fairly and middling are synonyms defined as:

Other synonyms of fairly include jolly, moderately, passably, pretty, reasonably, somewhat.

fairly (noun)	middling (noun)
	any commodity of intermediate quality or size (especially when coarse particles of ground wheat are mixed with bran)

fairly (adjective)	middling (adjective)
	lacking exceptional quality or ability

fairly (adverb)	middling (adverb)
without favoring one party, in a fair evenhanded manner	to certain extent or degree
to certain extent or degree
in conformity with the rules or laws and without fraud or cheating