Pronunciation: /ɛdʒ/ Explain

Geometric figure with dotted boundaries and solid boundaries.
Figure 1: Edges of a geometric figure.

  1. An edge of a 2-dimensional geometric figure is the boundary of the figure.[1] The figure does not extend beyond the boundary. The word 'edge' is usually used to refer to a straight edge. However both 'edge' and 'boundary' can be used to refer to a curve.
  2. An edge of a 3-dimensional polyhedron is the line formed by the intersection of two faces.
  3. An edge of a network graph is a path joining two nodes.

A boundary may or may not be included in the object. When graphing, a boundary that is not included in the object is conventionally drawn with a dotted line. A boundary that is included in the object is conventionally drawn with a solid line.


  1. McAdams, David E.. All Math Words Dictionary, edge. 2nd Classroom edition 20150108-4799968. pg 68. Life is a Story Problem LLC. January 8, 2015. Buy the book
  2. Stöcker, K.H.. The Elements of Constructive Geometry, Inductively Presented. pg 47. Translated by Noetling, William A.M, C.E.. www.archive.org. Silver, Burdett & Company. 1897. Last Accessed 7/9/2018. http://www.archive.org/stream/elementsofconstr00noetrich#page/47/mode/1up. Buy the book

Cite this article as:

McAdams, David E. Edge. 12/21/2018. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/e/edge.html.

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Revision History

12/21/2018: Reviewed and corrected IPA pronunication. (McAdams, David E.)
7/5/2018: Removed broken links, updated license, implemented new markup, implemented new Geogebra protocol. (McAdams, David E.)
8/5/2010: Added edge of a polyhedron and edge of a network graph. (McAdams, David E.)
12/31/2009: Added "References". (McAdams, David E.)
12/17/2008: Initial version. (McAdams, David E.)

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