retrospective vs backward

retrospective is a noun but backward is not a noun.

Word	Noun	Adjective	Verb	Adverb
retrospective	Yes	Yes	No	No
backward	No	Yes	No	Yes

retrospective (noun)	backward (noun)
an exhibition of a representative selection of an artist's life work

retrospective (adjective)	backward (adjective)
concerned with or related to the past	directed or facing toward the back or rear
	(used of temperament or behavior) marked by a retiring nature
	retarded in intellectual development
	having made less than normal progress

retrospective (adverb)	backward (adverb)
	in a manner or order or direction the reverse of normal
	in or to or toward a past time
	at or to or toward the back or rear