Usually applies to triangles, but also to regular polygons.

The point where the three medians of the triangle intersect. The 'center of gravity' of the triangle. One of a triangle's points of concurrency.

For more see Centroid of a triangle.

Pages referring to 'centroid'

A method to find the coordinates on the centroid of a triangle given the coordinates of the three vertices.
Animation showing that in any triangle, the centroid, circumcenter and orthocenter are always collinear - they always lie on a straight line, called the Euler line.
How to construct (draw) the centroid of a triangle with compass and straightedge or ruler. The centroid of a triangle is the point where its medians intersect. It is also the center of gravity of the triangle and one of the triangle's points of concurrency. It works by constructing two medians, which intersect at the centroid. A Euclidean construction.
Definition and properties of medians of a triangle
An overview of the various centers of a triangle
Definition and properties of the centroid of a triangle