English Reference
noun

hemisphere

n.
US /ˈhɛmɪsˌfɪɹ/ UK /hˈɛmɪsfˌiə/ hemi·sphere UK spelling hemisphere's, hemisphere's

  1. 01 B2 Upper Intermediate

    one half of the Earth, usually divided by the equator into north and south.

    one of the halves into which the Earth is divided, typically by the equator or a meridian.

    Simple

    In the Southern Hemisphere, the seasons are the opposite of those in Europe.

    In context

    Migratory patterns often involve birds traveling between the Northern and Southern Hemispheres to exploit seasonal abundance in different climates.

    Usage

    Usually capitalized when naming a specific one, such as the Northern Hemisphere.

  2. 02 B2 Upper Intermediate Technical Medicine

    one of the two halves of the human brain.

    either of the two symmetrical halves of the cerebrum in the brain.

    Simple

    The left hemisphere of the brain is often associated with language and logic.

    In context

    Neuroscientists have demonstrated that while certain functions are lateralized, both hemispheres communicate constantly through the corpus callosum.

    Usage

    Often used with 'left' or 'right'.

  3. 03 C1 Advanced Technical Math

    any half of a solid round shape or sphere.

    a half of a sphere, formed by a plane passing through its center.

    Simple

    The modern building was topped with a glass hemisphere that let in the light.

    In context

    The architect designed the ceiling as a perfect hemisphere, creating an acoustic environment where even a whisper could be heard across the hall.

    half sphere
  4. 04 C1 Advanced Technical Science

    half of the sky as seen from Earth.

    half of the celestial sphere as divided by the celestial equator or the ecliptic.

    Simple

    Certain constellations are only visible to people living in the northern hemisphere.

    In context

    Astronomers cataloged the stars of the southern hemisphere during the eighteenth-century expeditions, filling in gaps in the existing celestial maps.

Harbor porpoises and humans have been neighbors for thousands of years, living side-by-side along ocean coasts throughout the Northern Hemisphere.

Smithsonian Magazine· 14 Aug 2026

Together, the two observing sites greatly expand the geographic reach of the survey and allow SDSS-V to examine the sky from both hemispheres.

ScienceDaily· 14 Aug 2026

From Latin hemisphaerium, from Ancient Greek ἡμισφαίριον (hēmisphaírion), from ἡμι- (hēmi-, “half”) + σφαῖρα (sphaîra, “sphere”). Equivalent to hemi- + sphere. Displaced native Old English healftrendel (literally “half-sphere”).

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin Ancient Greek ἡμισφαίριον
Level B2 · Upper Intermediate
Frequency Frequent
Updated