|Noah Webster's Dictionary|
(n.) An optical illusion, seen frequently in deserts, looking like a pool of water due to total reflection of light at the surface common to two strata of air differently heated. The reflected image is seen, commonly in an inverted position, while the real object may or may not be in sight. When the surface is horizontal, and below the eye, the appearance is that of a sheet of water in which the object is seen reflected; when the reflecting surface is above the eye, the image is seen projected against the sky. The fata Morgana and looming are species of mirage.
Int. Standard Bible Encyclopedia
me-razh' (sharabh, "heat-mirage"; Arabic sarab, from verb which means "to go forth," "to flow"; hence, "flowing of water"): "The glowing sand shall become a pool, and the thirsty ground springs of water" (Isaiah 35:7); the King James Version has "parched ground" and the Revised Version margin "mirage." The same Hebrew word is also used in Isaiah 49:10, "Neither shall the heat (margin "mirage") nor sun smite them." These are the only uses of the word in the Scriptures, although mirages are very common in the drier parts of the country. However, the context in both cases seems to justify the translation usually given, rather than "mirage."
Alfred H. Joy
Mirage (2 Occurrences)
Isaiah 35:7 And the mirage shall become a pool, and the thirsty land springs of water: in the habitation of wild dogs, where they lay down, shall be grass with reeds and rushes. (DBY YLT)
Isaiah 49:10 They do not hunger, nor thirst, Nor smite them doth mirage and sun, For He who is pitying them doth lead them, And by fountains of waters doth tend them. (YLT)