Center: 1a. The point round which a circle is described; the middle point of a circle or sphere, equally distant from all points on the circumference.
4. The point, pivot, axis, or line round which a body turns or revolves; the fixed or unmoving centre of rotation or revolution.
6a. The point round which things group themselves or revolve, or that forms a nucleus or point of concentration for its surroundings. spec. (orig. U.S.) a place or a collection of buildings forming a central point in a town, district, etc., or the main area for a particular activity, interest, or the like