What word or phrase does your mother always say?
(plural loci), 1715, "locality," from Latin locus "a place, spot, position," from Old Latin stlocus, literally "where something is placed," from PIE root *st(h)el- "to cause to stand, to place." Used by Latin writers for Greek topos. Mathematical sense by 1750.
locus lo·cus (lō'kəs)
n. pl. lo·ci (-sī', -kē, -kī')
A place; site.
The position that a given gene occupies on a chromosome.
plur. loci (loh-seye, loh-keye)
In geometry, the set of all points (and only those points) that satisfy certain conditions; these points form a curve or figure. For example, the locus of all points in space one foot from a given point is a sphere having a radius of one foot and having its center at the given point. The locus of all points in a plane one foot from a given point is a circle having a radius of one foot and having its center at the given point.