disproof vs reductio

disproof and reductio both are nouns.

Word	Noun	Adjective	Verb	Adverb
disproof	Yes	No	No	No
reductio	Yes	No	No	No

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

disproof: any evidence that helps to establish the falsity of something
reductio: (reduction to the absurd) a disproof by showing that the consequences of the proposition are absurd; or a proof of a proposition by showing that its negation leads to a contradiction

Other hyponyms of disproof include reductio ad absurdum, confutation, counterexample.

disproof (noun)	reductio (noun)
the act of determining that something is false	(reduction to the absurd) a disproof by showing that the consequences of the proposition are absurd; or a proof of a proposition by showing that its negation leads to a contradiction
any evidence that helps to establish the falsity of something