An Etymological Dictionary of Astronomy and Astrophysics

An optical phenomenon caused by → refraction of light in the lowest layers of the Earth’s → atmosphere especially in the → desert, over a hot pavement, or at → sea. Due to temperature variations, the air → density varies, leading to a spatial variation of the → index of refraction of → air. As a result, light from a single point takes more than one path to the observer and the → image of some distant object appears displaced from its true position; the image may appear distorted, inverted, or wavering.

Etymology (EN): From Fr. mirage, from (se) mir(er) “to look at (oneself), be reflected”
(from L. mirare “to wonder at, admire”) + suffix -age.

Etymology (PE): Sarâb “mirage,” literally “water point, water origin, water head,”
probably from sar “origin, beginning,” → head, + âb, → water. The similarity with Ar. serab (cf. Hebrew sharab “burning heat, parched ground”) may be fortuitous.