Definition of negation :
1. Description or definition by denial, exclusion, or exception; statement of what a thing is not, or has not, from which may be inferred what it is or has.
2. The act of denying; assertion of the nonreality or untruthfulness of anything; declaration that something is not, or has not been, or will not be; denial; - the opposite of affirmation.
denial (part of speech: noun)
counter-evidence (part of speech: noun)
negation (part of speech: noun)
opposite (part of speech: noun)
annulment (part of speech: noun)
disavowal, nullification, elimination, abnegation, destruction, extinguishment, cancellation, dissolution, disaffirmation, eradication, refutation, dismissal, repudiation, obliteration, abolition, invalidation, disclamation, neutralization, abolishment, undoing, revocation, rejection, withdrawal, divorce, deletion, annulment, denial, retraction