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

The Lydia dress, which borrows the look of more contemporary pieces from the Royal Ballet, used the same hem circumference measurement as the company’s dresses. —Hikmat Mohammed, Footwear News, 8 Oct. 2025

The widest tree in Indiana, according to the registry, is a Silver Maple in Lawrence County with a circumference of 361 inches and a height of 103 feet. —John Tufts, IndyStar, 3 Oct. 2025

Researchers use three methods for assessing child malnutrition – either a child’s height and weight, their BMI, or a child’s mid-upper arm circumference, known as MUAC. —Soph Warnes, CNN Money, 2 Oct. 2025

Under the memo from Hegseth, the height-waist circumference method will be evaluated twice a year. —Luis Martinez, ABC News, 1 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