Definitions of locus:

• noun:   the set of all points or lines that satisfy or are determined by specific conditions

  Example: "The locus of points equidistant from a given point is a circle"

• noun:   the specific site of a particular gene on its chromosome
• noun:   the scene of any event or action (especially the place of a meeting)
• name:  A surname (very rare: popularity rank in the U.S.: #46546)