feebleminded vs backward

feebleminded and backward both are adjectives.

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

As adjectives, feebleminded and backward are synonyms defined as:

Other synonyms of feebleminded include half-witted, slow-witted.

feebleminded (adjective)	backward (adjective)
retarded in intellectual development	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

feebleminded (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