toss-up vs hazard

toss-up and hazard both are nouns.

Word	Noun	Adjective	Verb	Adverb
toss-up	Yes	No	No	No
hazard	Yes	No	Yes	No

As nouns, hazard is a hypernym of toss-up; that is, hazard is a word with a broader meaning than toss-up:

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

Other hypernyms of toss-up include chance, fortune, luck.

toss-up (noun)	hazard (noun)
an unpredictable phenomenon	an obstacle on a golf course
	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

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