hemi·​sphere | \ ˈhe-mə-ˌsfir How to pronounce hemisphere (audio) \

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 1a(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 How to pronounce hemispheric (audio) , -​ˈsfer-​ \ or hemispherical \ ˌhe-​mə-​ˈsfir-​i-​kəl How to pronounce hemispherical (audio) , -​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 On the flip side of the hemisphere, winter normally blankets the historic Moscow roads starting in October or November. Daniel Wolfe, Quartz, "The climate is changing—New Year’s Eve celebrations should too," 31 Dec. 2019 The zone moves to whichever hemisphere, north or south, is warmest at the time. Robin George Andrews, National Geographic, "The ghosts of ancient hurricanes live in Caribbean blue holes," 11 Nov. 2019 Also from the pop hemisphere, chart-topping artists like Billboard Hot 100-reigning Lizzo, current Billboard cover star Kesha, Billboard 200-peaking Post Malone, Ariana Grande or Bruno Mars make for top contenders for the performance slot. Heran Mamo, Billboard, "Who Should Sing the National Anthem Before Super Bowl 2020? Vote!," 30 Sep. 2019 In the world of social media, Facebook practically takes up an entire hemisphere of real estate. Shirley Li, The Atlantic, "How a Show About Grief Created a Community," 1 Oct. 2019 For example, the CDC’s forecasts are limited to national and regional levels but investigators have begun to consider the prospects for city-scale forecasts, as well as forecasting across global hemispheres. Charles Schmidt, Scientific American, "Real-time flu tracking," 18 Sep. 2019 This trail, spotted for the first time (seen above as the faint track between the two red arrows), is part of a longer stream that’s responsible for the Geminid meteor shower, an annual light show that peaks today and tomorrow in both hemispheres. Katherine Kornei, Science | AAAS, "Spacecraft spots asteroid debris responsible for spectacular meteor shower," 13 Dec. 2019 The homicide rate — among the highest in the hemisphere — plunged. Washington Post, "Disappeared in El Salvador: Amid the return of a Cold War nightmare, one body and three grieving families," 19 Oct. 2019 There has to be a way for people to live in the hemisphere. Jonathan Blitzer, The New Yorker, "Does Asylum Have a Future at the Southern Border?," 3 Oct. 2019

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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Time Traveler for hemisphere

Time Traveler

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

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Statistics for hemisphere

Last Updated

21 Jan 2020

Cite this Entry

“Hemisphere.” The Merriam-Webster.com Dictionary, Merriam-Webster Inc., https://www.merriam-webster.com/dictionary/hemisphere. Accessed 23 January 2020.

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More Definitions for hemisphere


How to pronounce hemisphere (audio)

English Language Learners Definition of hemisphere

: a half of the Earth
: half of a sphere : half of a round object
technical : either of the two halves of the brain


hemi·​sphere | \ ˈhe-mə-ˌsfir How to pronounce hemisphere (audio) \

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 How to pronounce hemisphere (audio) \

Medical Definition of hemisphere

: half of a spherical structure or organ: as
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

Comments on hemisphere

What made you want to look up hemisphere? Please tell us where you read or heard it (including the quote, if possible).


out of the ordinary or unreasonable

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