An Etymological Dictionary of Astronomy and Astrophysics

A curve which lies on a cylinder or cone, so that its angle to a plane perpendicular to the axis is constant.

Etymology (EN): From L. helix “spiral,” from Gk. helix (genitive helikos), related to eilein “to turn, twist, roll.”

Etymology (PE): Picâr “that which twists,” from
pic, present stem of picidan “to twist, entwine, coil” + -ar agent noun suffix (on the model of parastâr, padidâr, dustâr, xâstâr).