autoerotism vs onanism

autoerotism and onanism both are nouns.

Word	Noun	Adjective	Verb	Adverb
autoerotism	Yes	No	No	No
onanism	Yes	No	No	No

As nouns, onanism is a hyponym of autoerotism; that is, onanism is a word with a more specific, narrower meaning than autoerotism:

autoerotism: using your own body as a sexual object
onanism: manual stimulation of the genital organs (of yourself or another) for sexual pleasure

Other hyponyms of autoerotism include masturbation.

autoerotism (noun)	onanism (noun)
using your own body as a sexual object	manual stimulation of the genital organs (of yourself or another) for sexual pleasure
	a method of birth control in which coitus is initiated but the penis is deliberately withdrawn before ejaculation