In geometry, a centre (or center) (from Greek κέντρον) of an object is a point in some sense in the middle of the object. According to the specific definition of center taken into consideration, an object might have no center. If geometry is regarded as the study of isometry groups then a centre is a fixed point of all the isometries which move the object onto itself.

In geometry, a centre (or center) (from Greek κέντρον) of an object is a point in some sense in the middle of the object. According to the specific definition of center taken into consideration, an object might have no center. If geometry is regarded as the study of isometry groups then a centre is a fixed point of all the isometries which move the object onto itself.