It means:
* To make something ineffective or invalid.
* To deny the truth or existence of something.
For example:
* "The warm weather negated the need for a coat."
* "His alibi negated his involvement in the crime."
It means:
* To make something ineffective or invalid.
* To deny the truth or existence of something.
For example:
* "The warm weather negated the need for a coat."
* "His alibi negated his involvement in the crime."