center of gravity(point, near or within a body, at which the object's mass can be assumed to be concentrated) noun [UK: ˈsen.tə(r) əv ˈɡræ.vɪ.ti] [US: ˈsen.tər əv ˈɡræ.və.ti]
centre of mass(point where the mass can be considered concentrated) noun [UK: ˈsen.tə(r) əv mæs] [US: ˈsen.tər əv ˈmæs]