According to the Merriam Webster Dictionary circumference is "the perimeter of a circle" or "the external boundary or surface of a figure or object". In the picture we can see an example of circumference, a ferris-wheel.
According to the Etymology Dictionary circumference comes from Latin circumferentia. Circumference is composed by circum- "around" and -ferre "to carry".
Circumpolar has got the same roots as circumference. Other words with the root circum- are: circumnavigate, circumspect, circumflex.
Other words with the root ferr- are: ferry, reference , ferris wheel.