The Free On-line Dictionary of Computing (30 December 2018):

constructive solid geometry
CSG

    (CSG) A method used in solid modeling to describe the
   geometry of complex three-dimensional scenes by applying set
   operations (union, difference, intersection) to primitive
   shapes (cuboids, cylinders, prisms, pyramids, spheres and cones).

   See also CSG-tree.

   CSG in JavaScript (http://evanw.github.io/csg.js/).

   (2014-09-22)