An Etymological Dictionary of Astronomy and Astrophysics

General: The act or process of separating. The place at which a division or parting occurs.
Astro.: The angular distance between the two components of a visual binary or optical double star.

Etymology (EN): M.E., from O.Fr. separation, from L. separationem, from separare “to pull apart,” from se- “apart” + parare “make ready, prepare.”

Etymology (PE): Jodâyi state noun of jodâ “separate,” from Mid.Pers. yut “separate, different;” Av. yuta- “separate, apart.”