negation

noun

1. 1

   The act of negating something.

2. 2

   A denial or contradiction.

3. 3

   A proposition which is the contradictory of another proposition and which can be obtained from that other proposition by the appropriately placed addition/insertion of the word "not". (Or, in symbolic logic, by prepending that proposition with the symbol for the logical operator "not".)

4. 4

   The logical operation which obtains such (negated) propositions.