loca

Webster's Dictionary (GCIDE)

Locus \Lo"cus\, n.; pl. Loci, & Loca. [L., place. Cf. Allow, Couch, Lieu, Local.]

1.A place; a locality. [1913 Webster]

2.(Math.) The line traced by a point which varies its position according to some determinate law; the surface described by a point or line that moves according to a given law. [1913 Webster]

Plane locus, a locus that is a straight line, or a circle.

Solid locus, a locus that is one of the conic sections. [1913 Webster]