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.