centre of mass

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

• noun Australia, New Zealand, UK, Canada a point, near, or within a body at which the object's mass can be assumed to be concentrated; it coincides with the centroid for a body of uniform density, and with the centre of gravity in a uniform gravitational field

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun point representing the mean position of the matter in a body