hemi·​sphere | \ˈhe-mə-ˌsfir \

Definition of hemisphere 

1a : a half of the celestial sphere as divided into two halves by the horizon (see horizon sense 1b), the celestial equator, or the ecliptic

b : half of a spherical or roughly spherical body (such as a planet) specifically : the northern or southern half of the earth as divided by the equator (see equator sense 2) or the eastern or western half as divided by a meridian (see meridian sense 4a(2)) affected by the weather in the other hemisphere

c : the inhabitants of a hemisphere of the Earth

2 : an area of knowledge or activity : sphere, province a hemisphere of life heretofore unknown to us

3 : one of two half spheres (see sphere entry 1 sense 2a) formed by a plane (see plane entry 1 sense 2a) through the sphere's center : half of a round object

4 : a map or projection of a celestial hemisphere (see hemisphere sense 1a) or a terrestrial hemisphere (see hemisphere sense 1b)

5 : cerebral hemisphere an injury to the left hemisphere

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Other Words from hemisphere

hemispheric \ˌhe-​mə-​ˈsfir-​ik, -​ˈsfer-​ \ or hemispherical \ˌhe-​mə-​ˈsfir-​i-​kəl, -​ˈsfer-​ \ adjective

Did You Know?

Hemisphere includes the prefix hemi-, meaning "half". The northern and southern hemispheres are divided by the equator, the circle halfway between Earth's two poles. The eastern and western hemispheres aren't divided so exactly, since there are no poles in the Earth's east-west dimension. Often the dividing line is said to be the "prime meridian"—the imaginary north-south line that runs through Greenwich, England, from which all longitude is calculated (itself being the 0° meridian). But for simplicity's sake, the eastern hemisphere is often said to include all of Europe, Africa, Australia, and Asia, while the western hemisphere contains North and South America and a great deal of ocean.

Examples of hemisphere in a Sentence

a tumor in the right cerebral hemisphere

Recent Examples on the Web

The growth in drug trafficking has fueled violence in Honduras, one of the hemisphere’s poorest countries that has one of the world’s highest murder rates. Ryan Dube, WSJ, "U.S. Files Drug Charges Against Brother of Honduran President," 26 Nov. 2018 The occipital lobe is one of the four major lobes of the cerebral cortex, the thick outer layer of gray matter covering our noggins’ hemispheres. Beth Mole, Ars Technica, "Doctors cut out a large chunk of a boy’s brain—now he’s doing just fine," 1 Aug. 2018 To speak of this hemisphere alone, Haiti and Nicaragua are undergoing violent political turmoil these days. Fabiola Santiago, miamiherald, "Another separation crisis looms – this time for some 273,000 American children," 12 July 2018 The timing could not be worse for Venezuela’s increasingly authoritarian president, Nicolás Maduro, who was re-elected last month in a vote that has been widely condemned by leaders across the hemisphere. New York Times, "Workers Flee and Thieves Loot Venezuela’s Reeling Oil Giant," 14 June 2018 The statement by Maduro came two days after his reelection victory in a vote that was condemned as illegitimate by the United States and nations across the hemisphere. Anthony Faiola And Rachelle Krygier, BostonGlobe.com, "Venezuela announces the expulsion of two top US diplomats," 23 May 2018 The statement by Maduro came two days after his reelection victory in a vote that was condemned as illegitimate by the United States and nations across the hemisphere. Washington Post, "Venezuela announces the expulsion of two top U.S. diplomats," 22 May 2018 These involved nearly half of all electrodes and occurred in all lobes and both hemispheres of patients’ brains. Simon Makin, Scientific American, "“Traveling” Brain Waves May Be Critical for Cognition," 28 June 2018 Yes, the French team has roots stretching across borders, seas and hemispheres, tracing histories of colonization and the paths of migration that shaped today's world. Fox News, "Migration, outreach mean diversity is soccer's new normal," 10 July 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'hemisphere.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of hemisphere

14th century, in the meaning defined at sense 1a

History and Etymology for hemisphere

Middle English hemispere, from Latin hemisphaerium, from Greek hēmisphairion, from hēmi- + sphairion, diminutive of sphaira sphere

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Last Updated

9 Dec 2018

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The first known use of hemisphere was in the 14th century

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More Definitions for hemisphere



English Language Learners Definition of hemisphere

: a half of the Earth

: half of a sphere : half of a round object

: either of the two halves of the brain


hemi·​sphere | \ˈhe-mə-ˌsfir \

Kids Definition of hemisphere

1 : one of the halves of the earth as divided by the equator or by a meridian

2 : a half of a sphere

3 : either the left or the right half of the cerebrum

Other Words from hemisphere

hemispheric \ˌhem-​ə-​ˈsfir-​ik, -​ˈsfer-​ \ or hemispherical \-​ˈsfir-​i-​kəl, -​ˈsfer-​ \ adjective


hemi·​sphere | \-ˌsfi(ə)r \

Medical Definition of hemisphere 

: half of a spherical structure or organ: as

a : cerebral hemisphere

b : either of the two lobes of the cerebellum of which one projects laterally and posteriorly from each side of the vermis

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More from Merriam-Webster on hemisphere

Rhyming Dictionary: Words that rhyme with hemisphere

Spanish Central: Translation of hemisphere

Nglish: Translation of hemisphere for Spanish Speakers

Britannica English: Translation of hemisphere for Arabic Speakers

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a soft lustrous wool fabric with mohair

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