An Etymological Dictionary of Astronomy and Astrophysics

1. The point that is equidistant from all the points on a circle or sphere.
   

2a) To place in or on a center.

2b) Telescope: To move a telescope in order to place the object of interest on the center of the field. → center of attraction, → center of gravity, → center of inertia, → center of mass, → center wavelength, → anticenter, → apocenter, → barycenter, → optical center, → pericenter.

Etymology (EN): M.E. centre, from O.Fr. centre, from L. centrum “center,” originally fixed point of the two points of a compass, from Gk. kentron “sharp point, goad,” from kentein “stitch,” from PIE
*kent- “to prick.”

Etymology (PE): Markaz “center,” from Ar.;
kayân, Mod.Pers. “the point made by the compasses, that is the center of a circle” [Dehxodâ]; markazidan, infinitive from markaz, → center,

• -idan infinitive suffix.