nullify

As a noun taxonomy

is the science or the technique used to make a classification.

As a verb nullify is

(legal) to make legally invalid.

Revoke is a synonym of nullify.

As verbs the difference between nullify and revoke

is that nullify is to make legally invalid while revoke is to cancel or invalidate by withdrawing or reversing.

As a noun revoke is

the act of revoking in a game of cards.

Nullify is a synonym of repeal.

As verbs the difference between repeal and nullify

is that repeal is to cancel, invalidate, annul while nullify is to make legally invalid.

As a noun repeal

is an act or instance of repealing.

As verbs the difference between mitigate and nullify

is that mitigate is to reduce, lessen, or decrease while nullify is to make legally invalid.

As verbs the difference between counteract and nullify

is that counteract is to act in opposition to; thwart; to hinder, defeat, or frustrate, by contrary agency or influence; as, to counteract the effect of medicines; to counteract good advice while nullify is to make legally invalid.

As verbs the difference between nullify and disinvent

is that nullify is (legal) to make legally invalid while disinvent is to nullify a previous invention.