circumference

American  

[ser-kuhm-fer-uhns] / sərˈkʌm fər əns /

noun

1. the outer boundary, especially of a circular area; perimeter.

   the circumference of a circle.

   Synonyms:

   circuit, periphery

2. the length of such a boundary.

   a one-mile circumference.

3. the area within a bounding line.

   the vast circumference of his mind.

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circumference British  

/ səˌkʌmfəˈrɛnʃəl, səˈkʌmfərəns /

noun

1. the boundary of a specific area or geometric figure, esp of a circle

2. the length of a closed geometric curve, esp of a circle. The circumference of a circle is equal to the diameter multiplied by π

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circumference Scientific  

/ sər-kŭm′fər-əns /

1. The boundary line of a circle.

2. The boundary line of a figure, area, or object.

3. The length of such a boundary. The circumference of a circle is computed by multiplying the diameter by pi.

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circumference Cultural  

1. The measure of the distance around a circle.

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Other Word Forms

Derived Forms

• circumferential
  adjective
• circumferentially
  adverb

Etymology

Origin of circumference

1350–1400; Middle English < Late Latin circumferentia, equivalent to circum- circum- + fer- (stem of ferre to carry) + -entia -ence

Explanation

The distance around a circle is called the circumference, and although circumference is often used when talking about round things, it can mean a boundary of any shape that completely surrounds something. It’s no coincidence that the first part of circumference looks like circle. The Latin word circum means “around,” and the root ferre is the Latin verb for “carry,” so imagine carrying a puppy around a circle pit of lava: the path you walk is the circumference. If you want to buy a new hat, you’ll need to measure the circumference of your head, and patrolling the circumference of your castle is a good way to protect against dragons.

Example Sentences

And it was a nerve-shredding putt from inside three feet that travelled most of the circumference of the hole before dropping that deservedly saw Korda home.

From BBC • Jun. 8, 2026

Patients also showed improvements relative to placebo on key secondary goals of the trial including waist circumference, blood glucose and blood pressure, they added.

From The Wall Street Journal • Feb. 24, 2026

UBT251 led to a mean weight loss of 19.7% after 24 weeks of treatment and also improved patients’ waist circumference, blood glucose, blood pressure, and lipids relative to placebo, the companies said.

From Barron's • Feb. 24, 2026

Because head circumference in newborns is strongly linked to brain size and later measures of intelligence, the research team examined both finger ratios and head size in a group of 225 newborns.

From Science Daily • Feb. 10, 2026

During the days, he walked the circumference of the island and found nothing of interest—unless you liked beaches and endless sea in every direction.

From "The House of Hades" by Rick Riordan

Related Words

• girth