hazard vs tossup

hazard and tossup both are nouns.

Word	Noun	Adjective	Verb	Adverb
hazard	Yes	No	Yes	No
tossup	Yes	No	No	No

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

hazard: an unknown and unpredictable phenomenon that causes an event to result one way rather than another
tossup: an unpredictable phenomenon

Other hyponyms of hazard include bad luck, mischance, mishap, even chance, toss-up.

hazard (noun)	tossup (noun)
an obstacle on a golf course	an unpredictable phenomenon
an unknown and unpredictable phenomenon that causes an event to result one way rather than another
a source of danger; a possibility of incurring loss or misfortune

hazard (verb)	tossup (verb)
put forward, of a guess, in spite of possible refutation
take a risk in the hope of a favorable outcome
put at risk