An Etymological Dictionary of Astronomy and Astrophysics

The aggregate of all possible positions of a moving or generating element, e.g. the locus of points equidistant from a given point is a circle whose center is the given point.

Etymology (EN): From L. locus “place,” from Old L. stlocus, literally “where something is placed,” from PIE base *st(h)el- “to cause to stand, to place.”

Etymology (PE): Mahalgân, from mahal “place, locality” + -gân relation and multiplicity suffix.