adequate vs fair to middling

adequate and fair to middling both are adjectives.

Word	Noun	Adjective	Verb	Adverb
adequate	No	Yes	No	No
fair to middling	No	Yes	No	No

As adjectives, adequate and fair to middling are synonyms defined as:

Other synonyms of adequate include passable, tolerable.

adequate (adjective)	fair to middling (adjective)
having the requisite qualities or resources to meet a task	about average; acceptable
about average; acceptable
sufficient for the purpose