semicircle

American  

[sem-i-sur-kuhl] / ˈsɛm ɪˌsɜr kəl /

noun

1. Also called semicircumference.  half of a circle; the arc from one end of a diameter to the other.

2. anything having or arranged in the form of a half of a circle.

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semicircle British  

/ ˌsɛmɪˈsɜːkjʊlə, ˈsɛmɪˌsɜːkəl /

noun

1. 1. one half of a circle

   2. half the circumference of a circle

2. anything having the shape or form of half a circle

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Other Word Forms

• semicircular adjective
• semicircularly adverb
• semicircularness noun

Etymology

Origin of semicircle

From the Latin word sēmicirculus, dating back to 1520–30. See semi-, circle

Example Sentences

For instance, traveling from the North Pole to the South Pole along Earth's surface follows a semicircle, which represents the shortest possible route on a sphere.

From Science Daily • Mar. 9, 2026

When you put it on you see before you four empty wooden chairs ranged in a semicircle.

From The Wall Street Journal • Jan. 22, 2026

Doors opened and shut, and people began to emerge, gathering into a semicircle.

From Slate • Oct. 27, 2025

Rivas hit “record” on her phone as a semicircle of trucks and vans came into view.

From Salon • Oct. 24, 2025

Here another ten rats stood, baffled, in a semicircle.

From "Mrs. Frisby and the Rats of NIMH" by Robert C. O'Brien