means The act of denying, contradicting, or making something not so — the logical or grammatical move that turns a statement into its opposite.

from From Latin negatio, the noun of negare, 'to say no, to deny' — built on the little stem neg-, the same flat refusal hiding inside negative, deny, and renege. That neg- traces back to an old Indo-European root meaning 'not,' the universal human gesture of shaking the head, dressed up in scholarly robes and carried into English through Old French in the late medieval period.