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

In a 2020 study, participants who followed a ketogenic diet experienced significant reductions in waist and hip circumference and total body fat percentage, without reducing their calorie intake. —Bret Scher, San Diego Union-Tribune, 5 Feb. 2026

This underground ring, 27 kilometers in circumference and straddling the border between France and Switzerland, was built to slam subatomic particles together at near light speed and test deep theories of the universe. —IEEE Spectrum, 3 Feb. 2026

Users can manually enter ear spacing and head circumference to fine-tune time-of-arrival differences, adjust virtual speaker angles between 40°, 60°, and 80° and enable optional room simulation for a consistent, dependable reference environment. —Mark Sparrow, Forbes.com, 21 Jan. 2026

The height of the knee-high shaft height measures 375mm, and have a 175mm circumference. —Karla Rodriguez, Footwear News, 16 Jan. 2026

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