Perimeter
Part of speech: noun
Definition: The sum of the distance of all the lengths of the sides of an object. The outer limits of an area. See Synonyms at circumference. The length of such a boundary. A fortified strip or boundary usually protecting a military position.
Circumference
Part of speech: noun
Definition: The line that bounds a circle or other two-dimensional figureThe length of such a lineThe surface of a round or spherical object