cyclide

from The Century Dictionary.

• noun In geometry, the envelop of a sphere touching three fixed spheres.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Geom.) A surface of the fourth degree, having certain special relations to spherical surfaces. The tore or anchor ring is one of the cyclides.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun mathematics Any of a class of surfaces, described by quartic expressions, that are related to spherical surfaces