fecal matter vs dirt

fecal matter and dirt both are nouns.

Word	Noun	Adjective	Verb	Adverb
fecal matter	Yes	No	No	No
dirt	Yes	Yes	No	No

As nouns, dirt is a hyponym of fecal matter; that is, dirt is a word with a more specific, narrower meaning than fecal matter:

Other hyponyms of fecal matter include dog do, dog shit, dog turd, doggy do, crap, poop, shit, shite, turd, droppings, dung, muck, meconium, melaena, melena.

fecal matter (noun)	dirt (noun)
solid excretory product evacuated from the bowels	disgraceful gossip about the private lives of other people
	anything regarded as making something unclean
	the part of the earth's surface consisting of humus and disintegrated rock
	obscene terms for feces

fecal matter (adjective)	dirt (adjective)
	(of roads) not leveled or drained; unsuitable for all year travel