dirty vs foul

dirty is not a noun while foul is a noun.

Word	Noun	Adjective	Verb	Adverb
dirty	No	Yes	Yes	No
foul	Yes	Yes	Yes	No

As adjectives, dirty and foul are synonyms defined as:

Other synonyms of dirty include marked-up.

As adjectives, dirty and foul are synonyms defined as:

Other synonyms of dirty include cheating, unsporting, unsportsmanlike.

As verbs, foul is a hyponym of dirty; that is, foul is a word with a more specific, narrower meaning than dirty:

Other hyponyms of dirty include contaminate, pollute, smear, slime, muddy, muddy up, splash, mire, muck, muck up, mud, crock, blemish, spot.

dirty (noun)	foul (noun)
	an act that violates the rules of a sport

dirty (adjective)	foul (adjective)
soiled or likely to soil with dirt or grime	(of a baseball) not hit between the foul lines
(of behavior or especially language) characterized by obscenity or indecency	disgustingly dirty; filled or smeared with offensive matter
spreading pollution or contamination; especially radioactive contamination	characterized by obscenity
unethical or dishonest	(of a manuscript) defaced with changes
expressing or revealing hostility or dislike	offensively malodorous
obtained illegally or by improper means	highly offensive; arousing aversion or disgust
(of a manuscript) defaced with changes	especially of a ship's lines etc
(of color) discolored by impurities; not bright and clear	violating accepted standards or rules
vile; despicable
contaminated with infecting organisms
unpleasantly stormy
violating accepted standards or rules

dirty (verb)	foul (verb)
make soiled, filthy, or dirty	become soiled and dirty
	make unclean
	spot, stain, or pollute
	make impure
	commit a foul; break the rules
	hit a foul ball
	become or cause to become obstructed