means An optical illusion, especially the shimmering appearance of water on a hot road or desert, caused by light bending as it passes through air of different temperatures.

from From French mirage, born of the verb mirer, 'to look at, to be reflected,' which traces back to Latin mirari, 'to wonder at, to marvel' — the same root that gives us 'mirror' and 'miracle.' So at its heart, a mirage is literally a thing of wonder, a trick that makes you marvel; the word arrived in English in the early 19th century, fittingly around the time European travelers were sending back astonished accounts of deserts that seemed to flood and vanish.