onanism vs birth prevention

onanism and birth prevention both are nouns.

Word	Noun	Adjective	Verb	Adverb
onanism	Yes	No	No	No
birth prevention	Yes	No	No	No

As nouns, birth prevention is a hypernym of onanism; that is, birth prevention is a word with a broader meaning than onanism:

onanism: a method of birth control in which coitus is initiated but the penis is deliberately withdrawn before ejaculation
birth prevention: limiting the number of children born

Other hypernyms of onanism include birth control, family planning.

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a method of birth control in which coitus is initiated but the penis is deliberately withdrawn before ejaculation