retard vs idiot

retard and idiot both are nouns.

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

As nouns, retard and idiot are synonyms defined as:

Other synonyms of retard include changeling, cretin, half-wit, imbecile, moron.

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

retard (verb)	idiot (verb)
lose velocity; move more slowly
cause to move more slowly or operate at a slower rate
slow the growth or development of
be delayed