Pronunciation: /dɪˈmɛn ʃən/ Explain

A dimension is an extension in a particular direction.[1] A line has one dimension, since it extends in only one direction. A two dimensional space has two dimensions. An x-y graph is two dimensional. The x-axis defines one dimension and the y-axis defines another.

A dimension is not necessarily length. A dimension may also be temperature, time, mass, electrical current and others. For example, an equation may relate time and temperature: p = 2.5t where p represents temperature and t represents time. In this equation, one dimension is time and the other dimension is temperature. Albert Einstein's special theory of relativity deals with four dimensions: three dimensions are lengths making up a space, and one dimension is time. See also Dimensional Analysis.


An object is said to be dimensionless if it has no dimensions. The only object in most geometries that is dimensionless is a point.

A point has no dimensions.
1 dimensional
A line has one dimension.
2 dimensional
A two-variable Cartesian coordinate system has two dimensions.
3 dimensional
A three-variable Cartesian coordinate system has three dimensions.
2 dimensional
A rectangle has two dimensions (length and width).
3 dimensional
A sphere has three dimensions (length, width, and height).
4 dimensional
Euclidean space/time has four dimensions (length, width, height, and time).
Table 1: Dimensions

More Information

  • McAdams, David E.. Space. allmathwords.org. Life is a Story Problem LLC. 3/12/2009. http://www.allmathwords.org/en/s/space.html.

Cite this article as:

McAdams, David E. Dimension. 7/4/2018. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/d/dimension.html.

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Revision History

7/4/2018: Removed broken links, updated license, implemented new markup, implemented new Geogebra protocol. (McAdams, David E.)
1/23/2010: Added "References". (McAdams, David E.)
11/22/2009: Added manipulatives. (McAdams, David E.)
7/11/2008: Added table of dimensions. (McAdams, David E.)
7/7/2008: Corrected spelling errors. (McAdams, David E.)
5/7/2008: Added discussion of non-length dimensions. (McAdams, David E.)
3/10/2008: Initial version. (McAdams, David E.)
1/28/2008: Added link to Albert Einstein biography. (McAdams, David E.)

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