circumference

noun

cir·​cum·​fer·​ence sər-ˈkəm(p)-f(ə-)rən(t)s 

sə-,

-fərn(t)s

1

: the perimeter of a circle

The circle measures 22 inches in circumference.

2

: the external boundary or surface of a figure or object : periphery

from the center to the circumference of the sphere

circumferential

sər-ˌkəm(p)-fə-ˈren(t)-shəl 

sə-

adjective

Did you know?

Attempts have been made to measure the circumference of the earth since the time of Aristotle. The calculation that Columbus was relying on led him to think he could reach China by sailing west more quickly than by sailing east. But that measurement had calculated the earth's circumference as about a quarter too small, and the rest is history. Columbus wasn't the only one who got it wrong; many later attempts continued to produce different measurements for the earth's circumference—even though the Greeks had calculated it correctly way back in the 3rd century B.C.

Synonyms

• girth

Examples of circumference in a Sentence

What is the circumference of the Earth at the equator?

The circle is 38 inches in circumference.

The fence marks the circumference of the field.

Recent Examples on the Web

And that’s probably enough pie for one day for people watching their own circumferences. —Randy McMullen, The Mercury News, 13 Mar. 2025

March 14 is commonly referred to as Pi Day, a day that aims to celebrate the ratio of the circumference of a circle. —Gabe Hauari, USA TODAY, 13 Mar. 2025

Rachel does a great job conveying such collective endeavors and group dreaming, the whole circumference of people who support bands: friends of friends, drop-of-a-hat designers, stopgap agents, stall owners, dealers, grandparents with record collections, eccentrics without portfolios. —Ian Penman, Harper's Magazine, 19 Feb. 2025

That’s longer from end to end than the circumference of the Earth. —Mack Degeurin, Popular Science, 19 Feb. 2025

Word History

Etymology

Middle English, from Middle French & Latin; Middle French, from Latin circumferentia, from circumferre to carry around, from circum- + ferre to carry — more at bear

First Known Use

14th century, in the meaning defined at sense 1

Kids Definition

circumference

noun

cir·​cum·​fer·​ence sə(r)-ˈkəm(p)-fərn(t)s 

-f(ə-)rən(t)s

1

: a line that goes around or encloses a circle

2

: the outer boundary of a figure or area

3

: the distance around something

the circumference of the earth at the equator