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

Despite dropping what would have been a first-half bonus-point try, Kildunne accelerated on an outside arc and confidently dotted down with one hand.

From BBC • Apr. 11, 2026

Have you thought about how it will be to play Jimmy in the show’s fourth season now that this particular story arc has come to an end?

From Los Angeles Times • Apr. 9, 2026

Stories about recessions frequently adhere to a boom-to-bust narrative arc.

From Barron's • Apr. 3, 2026

Mullins hadn’t made a single one of his four 3-point attempts, and as the clock ticked down, he found himself standing closer to the half-court line than the arc.

From The Wall Street Journal • Mar. 30, 2026

Before I could finish baiting, another trout jumped at the falls, making the same lovely arc and disappearing into the water that was thundering down.

From "The Sun Also Rises" by Ernest Hemingway

Related Words

• arch