backward vs feebleminded

backward and feebleminded both are adjectives.

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

As adjectives, backward and feebleminded are synonyms defined as:

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

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

backward (adverb)	feebleminded (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