However - a much more serious definition is also had when it comes to the human mind. In psychology, Denial is defined as "a defense mechanism in which confrontation with a personal problem or with reality is avoided by denying the existence of the problem or reality"
Simply put, your mind says - nope - not dealing with that right now.
Left unchecked - these events fester and boil, causing fear and tensions - and we often self-medicate to alleviate the mental pain The compartmentalized issues can linger for years.
Interestingly - the 12 Step program has a great way of dealing with this. It's really nothing to do with alcohol directly - it's a mental health program with a spiritual core. Alcohol is a symptom, almost always of fear. Change the word "Alcohol" with "Fear" - suddenly it's a great therapy program.
Admit a problem that scares you, enlist a spiritual power - go over it - assess changes - make amends - move on.
Help others do the same.
So denial is one of quite a few brain tools to help us cope. The trick is to recognize is - work on it and not self-medicate over it. There is nothing in life that alcohol helps or makes better, and often a lot worse.
In running SoberWorld.org - there seems to be a huge denial of many things globally. Deaths, rapes, Cancers, the economic impact of alcohol and many more issues are largely ignored - and accepted. Personally, I find that unacceptable and will not live in denial.
"See what no one else sees - see what others choose not to see." - Patch Adams Movie.