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 of circumference

• diameter
• radius
• equator

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

Lilly‘s drug also showed improvement across factors like waist circumference, blood pressure, lipid profiles, glycemic control, and markers of inflammation. —Reuters, NBC news, 6 Nov. 2025

Unlike most wide calf boots, these boots have a circumference measurement that goes up when the shoe size goes up, in order to maintain their shape. —Amelia McBride, Travel + Leisure, 4 Nov. 2025

The silhouette featured an almond toe and stacked block heel, while the shaft made a unique statement with cinching at the ankle, a general looseness up the leg and then a lace threaded through the circumference about three-quarters of the way up, knotted in a bow as a dainty embellishment. —Jaden Thompson, Footwear News, 30 Oct. 2025

Its main beams are 27 inches long, with over 5-inch base circumferences. —Bob McNally, Outdoor Life, 30 Oct. 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