1. The line that goes round or encompasses a circular figure; a periphery.
2. A circle; anything circular.
His ponderous shield . . .
Behind him cast. The broad circumference
Hung on his shoulders like the moon. --Milton.
3. The external surface of a sphere, or of any orbicular body.
Cir·cum·fer·ence, v. t. To include in a circular space; to bound. [Obs.]
n 1: the size of something as given by the distance around it
2: the length of the closed curve of a circle