onanist vs tosser

onanist and tosser both are nouns.

Word	Noun	Adjective	Verb	Adverb
onanist	Yes	No	No	No
tosser	Yes	No	No	No

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

Other hyponyms of onanist include frotteur, jerk-off, wanker.

onanist (noun)	tosser (noun)
a person who practices masturbation	someone who throws lightly (as with the palm upward)
	terms of abuse for a masturbator