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

Humboldt Redwoods is home to The Giant Tree, which is set in the Rockefeller Forest and measures over 350 feet tall with a circumference of more than 50 feet. —Evie Carrick, Travel + Leisure, 9 Dec. 2025

Secure the entire circumference where the two trash bags meet with strong tape to prevent dust, moisture, pests, and odors from entering. —Maria Sabella, Better Homes & Gardens, 3 Dec. 2025

Instead of relying solely on BMI, which can miss where fat is stored, the team used a measurement of waist-to-hip ratio, which compares the circumference of the waist to the hips and determines how much fat sits around the abdomen. —Khloe Quill, FOXNews.com, 1 Dec. 2025

Workers using hydraulic hammers will chip away at the 160-foot-wide circumference and, in stages, each dome will collapse onto itself, about 8 feet at a time. —Rob Nikolewski, San Diego Union-Tribune, 1 Dec. 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