centres — Geometry. the middle point, as the point within a circle or sphere equally distant from all points of the circumference or surface, or the point within a regular polygon equally distant from the vertices.
insides — on the inner side or part of; within: inside the circle; inside the envelope.
interiors — being within; inside of anything; internal; inner; further toward a center: the interior rooms of a house.
bodies — the physical structure and material substance of an animal or plant, living or dead.
