It is called its bounds. In the case of 2 dimensional objects, it is part of the perimeter.
The outer edge means the furthest most point from the center. The outer edge is usually the end of the object before the dropping off point.
Perimeter
Its perimeter
outline
outline
It is called its bounds. In the case of 2 dimensional objects, it is part of the perimeter.
An outside border is a line or edge that surrounds the outer boundary of an object, such as a document, image, or table. It is often used to define the limits or separation of the object from its surroundings.
The leading edge
An edge can be of a shape in a plane while a rim suggests a three dimensional object with a defined outer portion. In geometry and topology "edge" has a definition which is very precise. "rim" haa no such specific determination.
Radius is from the center of a circle to the outer edge. Diameter is from the outer edge to the opposite outer edge, i.e., through the center. The diameter has twice the length of the radius.
The term that describes the outline of an object is "contour." It refers to the outer edge or silhouette of a shape or form. Contour lines are often used in art and design to define the shape and structure of an object.
The out edge of a cup is called the 'Rim'.