half-wit vs idiot

half-wit and idiot both are nouns.

Word	Noun	Adjective	Verb	Adverb
half-wit	Yes	No	No	No
idiot	Yes	No	No	No

As nouns, half-wit and idiot are synonyms defined as:

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

half-wit (noun)	idiot (noun)
a stupid incompetent person	a person of subnormal intelligence
a person of subnormal intelligence