masturbation vs onanism

masturbation and onanism both are nouns.

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

As nouns, masturbation and onanism are synonyms defined as:

masturbation and onanism: manual stimulation of the genital organs (of yourself or another) for sexual pleasure

masturbation (noun)	onanism (noun)
manual stimulation of the genital organs (of yourself or another) for sexual pleasure	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	a method of birth control in which coitus is initiated but the penis is deliberately withdrawn before ejaculation