hemisphere

• hemisphære (archaic)

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”).

• (Received Pronunciation) IPA^(key): /ˈhɛmɪsfɪə/
• (Standard Southern British) IPA^(key): /ˈhɛmɪsfɪː/, /ˈhɛmɪsfɪj.ə/
• (US, Canada) enPR: hĕm'ĭsfîr, IPA^(key): /ˈhɛmɪsfɪɹ/

  • Audio (US):

    (file)

• (General Australian) IPA^(key): /ˈhemɪsfɪə/
• (New Zealand) IPA^(key): /ˈheməsfiə/
• (Scotland) IPA^(key): /ˈhɛmɪsfiɾ/
• (East Anglia, cheer–chair merger) IPA^(key): /ˈhɛmɪsfɛː/

hemisphere (plural hemispheres)

1. (astronomy, astrology) Half of the celestial sphere, as divided by either the ecliptic or the celestial equator [from 14th c.].
2. (figuratively) A realm or domain of activity [1503].
   • 1831, L[etitia] E[lizabeth] L[andon], Romance and Reality. […], volume III, London: Henry Colburn and Richard Bentley, […], →OCLC, pages 91–92:

     Love is the Columbus of our moral world, and opens, at some period or other, a new hemisphere to our view.

3. (geography) Half of the Earth, such as the Northern Hemisphere, Southern Hemisphere, Western Hemisphere or Eastern Hemisphere, Land Hemisphere, Water Hemisphere etc. [1550s].
   • 2025 January 14, Jay Ganglani, Kocha Olarn, “59 degrees Fahrenheit might not sound that chilly. In Thailand’s capital, it’s a shock to the system”, in CNN‎^[1], archived from the original on 24 January 2025:

     Bangkok typically sees temperatures between 73 and 91 degrees Fahrenheit (23 to 33 degrees Celsius) during January, according to the Tourism Authority of Thailand – one reason why it’s a paradise for many tourists looking to escape winter in the northern hemisphere.

4. (geometry) Any half-sphere, formed by a plane intersecting the center of a sphere. [1580s].
5. (cartography) A map or projection of a celestial or terrestrial hemisphere [1706].
6. (anatomy) Either of the two halves of the cerebrum. [1804].

• (astronomy: half of the celestial sphere): celestial hemisphere
• (geography: half of the terrestrial sphere): terrestrial hemisphere
• (figuratively: a domain of thought or action): sphere
• (geometry: half of a sphere): half-sphere, half sphere
• (anatomy: either of the two lobes of the cerebellum): cerebral hemisphere
• (cartography: a map showing a projection of a hemisphere): planisphere

• → Welsh: hemisffer

• dome