pitch-dark vs dark

pitch-dark is not a noun while dark is a noun.

Word	Noun	Adjective	Verb	Adverb
pitch-dark	No	Yes	No	No
dark	Yes	Yes	No	No

pitch-dark (noun)	dark (noun)
	an unenlightened state
	an unilluminated area
	absence of light or illumination
	absence of moral or spiritual values
	the time after sunset and before sunrise while it is dark outside

pitch-dark (adjective)	dark (adjective)
extremely dark	devoid of or deficient in light or brightness; shadowed or black
	(used of color) having a dark hue
	brunet (used of hair or skin or eyes)
	secret
	causing dejection
	stemming from evil characteristics or forces; wicked or dishonorable
	showing a brooding ill humor
	not giving performances; closed
	marked by difficulty of style or expression
	lacking enlightenment or knowledge or culture