Definitions
1.AdverbIn, at, or towards the middle of a circle.
2.NounA circle that is in the middle.
3.NounThe middle of a circle.
4.NounThe middle of an act of circling.
5.NounThe great circle that is equidistant from two poles.
6.NounA reference generalised circle through which two given circles are inverses of each other.
7.NounThe circle (if one exists) that passes through the midpoint of each side of a given polygon, especially a triangle.