retard vs modify

retard is a noun but modify is not a noun.

Word	Noun	Adjective	Verb	Adverb
retard	Yes	No	Yes	No
modify	No	No	Yes	No

As verbs, modify is a hypernym of retard; that is, modify is a word with a broader meaning than retard:

Other hypernyms of retard include alter, change.

retard (noun)	modify (noun)
a person of subnormal intelligence

retard (verb)	modify (verb)
lose velocity; move more slowly	make less severe or harsh or extreme
cause to move more slowly or operate at a slower rate	add a modifier to a constituent
slow the growth or development of	cause to change; make different; cause a transformation
be delayed