What does 'cognitive closure' mean?

It is the point at which our brain is unable to understand or comprehend an idea or concept. For example: the end of the universe; or what happens to our consciousness after death. In animals it might be the use of language or the understanding of their mortality.

Re: Colin McGinn’s mysterianist approach to the phenomenon of consciousness. According to McGinn, consciousness is, in and of itself, a fully natural phenomenon, but we humans are just cognitively closed to it, meaning that we cannot in principle understand its nature.
Cognitive closure (psychology), a term describing the human desire to eliminate ambiguity and arrive at definite conclusions (sometimes irrationally).
Cognitive closure (philosophy), the idea that only certain things are even in principle understandable by beings like us. Used particularly to argue for the insolubility of certain problems in philosophy of mind.

http://www.consciousentities.com/mcginn.htm
https://en.wikipedia.org/wiki/Cognitive_closure