denial

The negation in logic.

“The denial of "There might be X" is the null, "False, there is no X."”

A refusal to comply with a request.

“Every time we asked for an interview we got a denial.”

An assertion of untruth.

“The singer has issued a sweeping denial of all the rumors.”

Refusal to believe a problem exists

“We couldn't break through his denial about being alcoholic.”

A defense mechanism involving a refusal to accept the truth of a phenomenon or prospect.

“He is in denial that he has a drinking problem.”