An Etymological Dictionary of Astronomy and Astrophysics

1. An apparently hollow formation in the structure of an astronomical object, for example a sizable hole on the surface of a → molecular cloud created by → ultraviolet photons of a → massive star.
   

2. In a semiconductor laser, two reflective parallel edges forming a resonator that amplifies the light through stimulated emission.

Etymology (EN): From M.Fr. cavité, from L.L. cavitas “hollowness,” from L. cavus “hollow.”

Etymology (PE): Kâvâk, related to verb kâvidan (kâftan) “to dig; to examine, investigate,” cf. L. cavus “hollow” (E. derivatives: cavity, concave, cave,
excavate), Gk. koilos “hollow,” Armenian sor,
PIE *kowos “hollow.”