Locus: A set of Points

G.GMD.4 . . . identify three-dimensional objects generated by rotations of two-dimensional objects.

A locus is a set of points, all of which meet a stated condition. Loci is the plural of locus.

The locus of points in the interior of an angle that are equidistant from the sides of the angle is an angle bisector.

In a plane, meaning the x and y axis, the locus of points that are equidistant from a segment's endpoints is the perpendicular bisector of the segment.