An Etymological Dictionary of Astronomy and Astrophysics

A closed curve lying in a plane and so constructed that all its points are equally distant from a fixed point in the plane.

Etymology (EN): From O.Fr. cercle, from L. circulus “small ring,” dim. of circus “ring,” from or akin to Gk. kirkos “a circle,” from PIE kirk- from base (s)ker- “to turn, bend,” related to Pers. carx “wheel, everything revolving in an orbit, circular motion, chariot.”

Etymology (PE): Parhun “circle” in Mod.Pers. classical texts, from Proto-Iranian *pari-iâhana- “girdle, belt,” from pari-, variant pirâ-, → circum-, + iâhana- “to girdle,” cf. Av. yâh- “to girdle.” The Pers. word pirâhan “shirt” is a variant of parhun. Gk. cognate zone “girdle."
Dâyeré, from Ar.