The center of mass of an object of uniform density WordNet 3.0 & Open English WordNet

In mathematics and physics, the centroid, also known as geometric center or center of figure, of a plane figure or solid figure is the point defined by the arithmetic mean position of all the points in the surface of the figure. Wikipedia

Mean position of all the points in the shape; mean position of all the points in all of the coordinate directions; point at which a cutout of the shape could be perfectly balanced on the tip of a pin Wikidata

The point at the centre of any shape, sometimes called centre of area or centre of volume. For a triangle, the centroid is the point at which the medians intersect. The co-ordinates of the centroid are the average (arithmetic mean) of the co-ordinates of all the points of the shape. For a shape of uniform density, the centroid coincides with the centre of mass which is also the centre of gravity in a uniform gravitational field. Wiktionary