Definition of "negation" in English

noun

1. (uncountable) The act of negating something.

2. (countable) A denial or contradiction.

3. (logic, countable) 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. (logic) The logical operation which obtains such (negated) propositions.