negation
n.the act of saying that something is not true or does not exist. You use this when you want to deny a statement.
n.the act of denying the truth or existence of something; the logical operation that produces a statement with the opposite truth value.
“The negation of 'the sky is blue' is 'the sky is not blue'.”
“In formal logic, the negation of a proposition is often represented by the symbol ¬.”
“The philosopher argued that the negation of a universal statement is not merely a simple 'no' but a complex assertion of the existence of a counterexample.”
From Middle English negacioun, from Old French negacion, from Latin negātiō (“a denial; negative word”). Morphologically negate + -ion.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.