An Etymological Dictionary of Astronomy and Astrophysics

The point on the celestial sphere directly above the observer’s head, opposite to the direction in which gravity acts. Opposite of → nadir.

Etymology (EN): M.E. cenith, from O.Fr. cenith, from M.L. cenit, senit, incorrect transliteration of Ar. samt (سمت) “path, direction,” abbreviation of samt ar-ras (سمت‌الرأس), literally “road above one’s head.”

Etymology (PE): Sarsu, literally “the way over the head,” from sar→ head + su, → direction.