• (n.) The center of a circle that circumscribes a triangle.
The center of a circle that passes through the vertices of a given polygon, usually a triangle. For a triangle, it is the same as the point of intersection of the perpendicular bisectors of the three sides.
Cir`cum·cen'ter noun (Geom.) The center of a circle that circumscribes a triangle. 
circumcenter 1. The center of a circumscribed circle. 2. That point where any two perpendicular bisectors of the sides of a polygon inscribed in the circle intersect.
the center of a circumscribed circle; that point where any two perpendicular bisectors of the sides of a polygon inscribed in the circle intersect.