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

• 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

Shortly after its debut this summer, the AMG team took the car to Nardò, a historic test track in Southern Italy, and drove the car 40,075 kilometers in 7 days, 13 hours, 24 minutes and 07 seconds – the equivalent of the Earth's circumference at the equator. —Eileen Falkenberg-Hull, MSNBC Newsweek, 25 Sep. 2025

These are more fitted than the typical straight-leg jeans and have a smaller hem circumference to tailor the ankles more. —Bestreviews, Mercury News, 22 Sep. 2025

Waist circumference also decreased slightly, though overall weight and blood sugar did not change. —Deirdre Bardolf, FOXNews.com, 16 Sep. 2025

Tree nominees are judged on trunk circumference, vertical height and crown spread. —Jennie Key, The Enquirer, 31 Aug. 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