an illusion
Examples
What if everything is an illusion and nothing exists? In that case, I definitely overpaid for my carpet.
Time is an illusion. Lunchtime doubly so.
There is no such thing as conversation. It is an illusion. There are intersecting monologues, that is all.
The secret to film is that it's an illusion.
Religion is an illusion and it derives its strength from the fact that it falls in with our instinctual desires.
For you who no longer posses it, freedom is everything, for us who do, it is merely an illusion.