Geometric locus

A concept sometimes employed in geometry. It is usually understood to mean the set of points (forming a curve or a surface in "good cases") which, out of all the points in the space, satisfy some geometric requirement. Thus, an ellipse may be defined as the geometric locus of points in the plane for which the sum of the distances from two given points is a constant magnitude.

Comments

The phrase "geometric locus" is somewhat obsolete, and nowadays usually simply means a point set defined by some property.

References

[a1]	H.S.M. Coxeter, "Introduction to geometry" , Wiley (1961)
[a2]	D. Hilbert, S.E. Cohn-Vossen, "Anschauliche Geometrie" , Springer (1932)