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• arc
  arc

  noun

  any unbroken part of the circumference of a circle or other curved line.
• ARC
  ARC

  noun

  AIDS-related complex.

arc

¹ American  

[ahrk] / ɑrk /

noun

1. Geometry. any unbroken part of the circumference of a circle or other curved line.

2. Also called electric arc.  Electricity. a luminous bridge formed in a gap between two electrodes.

3. Astronomy. the part of a circle representing the apparent course of a heavenly body.

4. anything bow-shaped.

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verb (used without object)

arced, arcked, arcing, arcking

1. to form an electric arc.

2. to move in a curve suggestive of an arc.

ARC ² American  

[ahrk] / ɑrk /

noun

1. Pathology. AIDS-related complex.

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ARC ³ American  

Or A.R.C.

abbreviation

1. American Red Cross.

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arc ¹ British  

/ ɑːk /

noun

1. something curved in shape

2. part of an unbroken curved line

3. a luminous discharge that occurs when an electric current flows between two electrodes or any other two surfaces separated by a small gap and a high potential difference

4. astronomy a circular section of the apparent path of a celestial body

5. maths a section of a curve, graph, or geometric figure

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verb

1. (intr) to form an arc

prefix

1. maths specifying an inverse trigonometric function: usually written arcsin , arctan , arcsec , etc, or sometimes sin–1 , tan–1 , sec–1 , etc

ARC ² British  

abbreviation

1. AIDS-related complex: an early condition in which a person infected with the AIDS virus may suffer from such mild symptoms as loss of weight, fever, etc

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arc Scientific  

/ ärk /

1. A segment of a circle.

2. See electric arc

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Etymology

Origin of arc

1350–1400; Middle English ark < Latin arcus bow, arch, curve

Explanation

An arc is a curve. You can describe the bend of a rainbow as an arc. In math, an arc is one section of a circle, but in life you can use the word to mean any curved shape, like the arc of a ballerina's arm or the graceful arc of a flowering vine over a trellis. In the 14th century, arc first meant the movement of the sun in the sky, from the Old French arc, "bow or arch," and the Latin root arcus, also "bow or arch."

Example Sentences

British oil giant Shell just made a big bet on Canadian shale oil and natural gas in a $16 billion deal to buy Calgary-based ARC Resources.

From Barron's • Apr. 28, 2026

Shell has agreed to buy Canadian shale company ARC Resources for $13.6 billion, in a move to boost its production capabilities at a time when prices have jumped.

From MarketWatch • Apr. 27, 2026

Last year, ARC reported production of 374,000 barrels of oil equivalent a day, before royalty burdens.

From The Wall Street Journal • Apr. 27, 2026

The ARC funding is part of a broader effort to study human origins.

From Science Daily • Mar. 22, 2026

ARC OF TRIUMPH, Paris, France.—This is the finest triumphal arch in existence.

From Shepp's Photographs of the World by Shepp, James W.

Related Words

• arch