just vs good

just is not a noun while good is a noun.

Word	Noun	Adjective	Verb	Adverb
just	No	Yes	No	Yes
good	Yes	Yes	No	Yes

As adjectives, just and good are synonyms defined as:

Other synonyms of just include upright.

just (noun)	good (noun)
	a raw material that is sold in large quantities, usually to other businesses for manufacturing or production purposes
	benefit
	moral excellence or admirableness
	that which is pleasing or valuable or useful

just (adjective)	good (adjective)
used especially of what is legally or ethically right or proper or fitting	having desirable or positive qualities especially those suitable for a thing specified
fair to all parties as dictated by reason and conscience	morally admirable
free from favoritism or self-interest or bias or deception; conforming with established standards or rules	promoting or enhancing well-being
of moral excellence	having the normally expected amount
	with or in a close or intimate relationship
	thorough
	generally admired
	resulting favorably
	not left to spoil
	not forged
	tending to promote physical well-being; beneficial to health
	in excellent physical condition
	appealing to the mind
	agreeable or pleasing
	exerting force or influence
	most suitable or right for a particular purpose
	capable of pleasing
	deserving of esteem and respect
	of moral excellence
	having or showing knowledge and skill and aptitude
	financially safe

just (adverb)	good (adverb)
and nothing more	(often used as a combining form) in a good or proper or satisfactory manner or to a high standard (`good' is a nonstandard dialectal variant for `well')
only a moment ago	completely and absolutely (`good' is sometimes used informally for `thoroughly')
(used for emphasis) absolutely
only a very short time before
indicating exactness or preciseness
exactly at this moment or the moment described
possibly (indicating a slight chance of something being true)
by a little