Mirage
Etymology
From French "mirage," from "se mirer" ("to be reflected, to look at oneself"), from Latin "mirari" ("to wonder at, marvel"). The same root gives us "mirror" and "miracle."
noun · /mih-RAHZH/
An optical illusion, such as a phantom sheet of water on a hot road, caused by light bending through air of different temperatures.
What it names
A specific trick of light — and doubles as a metaphor for any tempting illusion that vanishes as you approach.
Example
The road ahead shimmered with the mirage of a distant lake.
Related idea
A mirage is a real optical event caused by bending light; pareidolia is the mind imposing a familiar pattern, like a face, on random input.