hemisphere

American  

[hem-i-sfeer] / ˈhɛm ɪˌsfɪər /

noun

1. (often initial capital letter) half of the terrestrial globe or celestial sphere, especially one of the halves into which the earth is divided.

2. a map or projection representing one of these halves.

3. a half of a sphere.

4. Anatomy. either of the lateral halves of the cerebrum or cerebellum.

5. the area within which something occurs or dominates; sphere; realm.

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hemisphere British  

/ ˌhɛmɪˈsfɛrɪk, ˈhɛmɪˌsfɪə /

noun

1. one half of a sphere

2. 1. half of the terrestrial globe, divided into northern and southern hemispheres by the equator or into eastern and western hemispheres by some meridians, usually 0° and 180°

   2. a map or projection of one of the hemispheres

3. either of the two halves of the celestial sphere that lie north or south of the celestial equator

4. anatomy short for cerebral hemisphere

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hemisphere Scientific  

/ hĕm′ĭ-sfîr′ /

1. One half of a sphere, formed by a plane that passes through the center of the sphere.

2. Either the northern or southern half of the Earth as divided by the equator, or the eastern or western half as divided by a meridian, especially the prime meridian.

3. One half of the celestial sphere as divided by any of various great circles, especially the celestial equator and the ecliptic.

4. See more at celestial sphere

5. See cerebral hemisphere

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hemisphere Cultural  

1. Any half of the Earth's surface.

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Other Word Forms

• hemispheric
  adjective

Etymology

Origin of hemisphere

1325–75; < Latin hēmisphaerium < Greek hēmisphaírion; replacing Middle English emysperie < Old French emispere < Latin

Explanation

A hemisphere is half of a sphere. If it’s a cold winter in the northern hemisphere, take a winter getaway to sunbathe somewhere in the southern hemisphere. Hemisphere comes from the Greek, and combines the prefix hemi-, for "half," with sphere, or "perfectly round ball." We talk about the earth as divided at the equator into the northern and southern hemispheres (or divided at the prime meridian into eastern and western hemispheres). In biology, there are two cerebral, or brain, hemispheres — also known as the right and left sides of the brain.

Example Sentences

Its schedule shows it switches between southern and northern hemisphere summers.

From Barron's • May 4, 2026

“It was driven by the largest size hemisphere I could get in acrylic to make the visor,” Shearn, based in Colorado, said.

From Los Angeles Times • Apr. 10, 2026

By applying deep learning models trained on tens of thousands of MRI scans, the team estimated the "brain age" of different regions in each hemisphere and examined how stroke affects both structure and recovery.

From Science Daily • Mar. 29, 2026

Now we are past the spring equinox, the northern hemisphere starts to get more daylight and a strengthening Sun.

From BBC • Mar. 27, 2026

In radar astronomy, radio waves are transmitted by a telescope on Earth, strike, say, that hemisphere of Venus that happens to be facing the Earth, and bounce back.

From "Cosmos" by Carl Sagan

Related Words

• fraction