centre of mass

Centre of mass is the point where an object's mass is effectively concentrated—the average position of all its parts weighted by their mass.

A balanced object can be supported at its centre of mass without tipping.

For symmetrical objects of uniform density, it's the geometric center; for irregular objects, it may fall outside the physical body entirely.

The gymnast rotates around her centre of mass during a somersault.

Also spelled center of mass.