onomatomania vs obsession

onomatomania and obsession both are nouns.

Word	Noun	Adjective	Verb	Adverb
onomatomania	Yes	No	No	No
obsession	Yes	No	No	No

As nouns, obsession is a hypernym of onomatomania; that is, obsession is a word with a broader meaning than onomatomania:

onomatomania: obsession with a particular word which the person uses repeatedly or which intrudes into consciousness
obsession: an irrational motive for performing trivial or repetitive actions, even against your will

Other hypernyms of onomatomania include compulsion.

onomatomania (noun)	obsession (noun)
obsession with a particular word which the person uses repeatedly or which intrudes into consciousness	an unhealthy and compulsive preoccupation with something or someone
	an irrational motive for performing trivial or repetitive actions, even against your will