A hemisphere is a half-sphere, for example, half the Earth: northern, southern, eastern, western hemisphere.

In a forum post related to a ESA satellite station in Argentina, I came across the phrase "having such an strategic and experienced partner on the South West hemisphere".

Now obviously, the South West hemisphere is not a hemisphere, but a half-hemisphere. Is there a word for a quarter-sphere, south as, in the geographical case, the north west, north east, south west, south east?

Maybe something like quadrasphere?

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    What is meant by "western" or "eastern" hemisphere? I don't think this distinction would carry much meaning for most speakers. On the other hand, we have the Western world, but today this has "little geographical relevance". – Zairja Oct 31 '12 at 17:09
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    @Zairja Those of us who live practically on the Prime Meridian know what the western and eastern hemispheres are. The western hemisphere has longitude measured as "degrees west". – Andrew Leach Oct 31 '12 at 17:10
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    For the phrase "I have a quarter-sphere" Google Translate offers Έχω ένα τέταρτο-σφαίρα so it looks like the term should be tetartosphere. No-one but a Classics scholar will know what that is! – Andrew Leach Oct 31 '12 at 17:22
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    @gerrit Many Western Europeans are wrong. – user16269 Oct 31 '12 at 20:56
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    @DavidWallace I know they are. I just mean to illustrate it's not obvious to everybody. – gerrit Oct 31 '12 at 21:21

There is no such term. You could use semihemisphere, but this is not a geographical term as far as I'm aware. Evidence of absence is always difficult and doesn't make a rewarding answer.

I would suggest a different term altogether like area or region. If you insist on the "quarter of the earth" sense, then quadrant would fit your needs.

Carlo_R has an interesting point, but quadrant is in use, geographically, and is a word that most speakers will glean meaning from. Some examples include "Mapping World Heritage Sites":

Use a dry erase marker to draw, or have a volunteer draw, the Equator and prime meridian. Then label each quadrant of the map with its hemispheric identifier: NE, NW, SE, and SW.

"Geographic Coordinate System":

The origin of the graticule (0,0) is defined by where the equator and prime meridian intersect. The globe is then divided into four geographical quadrants that are based on compass bearings from the origin. North and south are above and below the equator, and west and east are to the left and right of the prime meridian.

Earth quadrant from Webster's (1913):

n. a fourth of the earth's circumference.

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    I disagree with "quadrant". In fact one curved quarter of the hemisphere is already a spherical quadrant of 90°, hence "quadrant" cannot be a quarter of a sphere. However, congratulations for "area" and "region". – user19148 Oct 31 '12 at 17:36
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    +1 for quadrant which makes sense since the "sphere" in question is inevitably a flattened 2-D translation. I would also mention octant which is its 3-D equivalent. – coleopterist Oct 31 '12 at 17:39
  • A quadrant of a circle is the area defined by 90 degrees of arc. So I think most geometers, at least, would think of a "quadrant" of a sphere as being a slice made up of 90 degrees of arc in one direction and 360 degrees in the other, not 180 and 180. – Jay Oct 31 '12 at 17:48
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    @What Carlo_R said. Rightly or wrongly, I would normally understand a quadrant of a sphere to look like the diagram in that link (one eighth of the total sphere). – FumbleFingers Oct 31 '12 at 17:56
  • I like "semihemisphere" or variations thereof. It's an obvious plagiarism of "semihemiquaver" from music. I don't think it's a recognized term, but it ought to be. – Jay Oct 31 '12 at 17:58

Why do you assume South West hemisphere is not correct? A sphere can be divided in half along any diameter, not just the Equator or zero meridian. I don't (obviously) know the original report, but it may easily be that the ESA meant the half of the world including Mexico and South Africa, but excluding Canada and Sri Lanka.

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    My objection to South West hemisphere is that hemisphere is 50% of the planet whereas South west (something) is 25% of the planet. I was quoting from a forum post, more specifically a Facebook comment on a ESA news item. – gerrit Oct 31 '12 at 20:11
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    @gerrit: My question is why do you assume Southwest is 25% while South is 50%? Both are arbitrary directions, and so both can equally refer to a hemisphere. – TimLymington Oct 31 '12 at 21:24
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    Hmmm... I didn't think of that option. But such a hemisphere would not go along either lines of latitude or lines of longitude. I have some difficulties imagining what it would look like. I'm pretty sure that in the context where I saw it, it meant 25%. – gerrit Oct 31 '12 at 21:30
  • Conceptually a "southwest hemisphere" should also include the northeast, if you were looking at a map. – Adam Starrh Aug 2 '16 at 15:36

There may be no official word for this in Geometry, but borrowing from semihemidemisemiquaver, a 1\128th note in music, you might use:


  • I like that better. It makes more sense to slice the sphere in half at each of its three orthogonal axes. – tchrist May 1 '14 at 0:06

If you want what would amount to one of eight pieces (rather than four) in three dimensions, and one of 2^n th in n dimensions, in mathematics, the term for the higher dimensional analogues of quadrant is orthant. This means—for three dimensions—one of the eight subsets, each consisting of triples with the same sign pattern. So you could say an orthant of the sphere, and anyone who knows the more general meaning of orthant would understand immediately.

Perhaps, bi-orthant (a set consisting of two, presumably contiguous, orthants) of a sphere would be what you want.


Qudrasphere - Hemisphere is half of the world, so quadrasphere could be one fourth of the world.


I suggest "Tetartosphere" (Tetarto - Greek: one-fourth)

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    please support your answer with some credible sources. – Bhoomika Arora May 22 '17 at 7:18
  • Yes, sounds interesting, but need the background on tetrato to make it more clear. – JeopardyTempest Jun 1 '18 at 14:44

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