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[koh-pley-ner] /koʊˈpleɪ nər/
adjective, Mathematics
being or operating in the same plane.
Origin of coplanar
1860-65; co- + planar < Late Latin plānāris; see plane1, -ar1
Related forms
coplanarity, noun
noncoplanar, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for coplanar
  • Actually, make that four non-coplanar points plus a fixed ordering of them.
  • The important consequence of both possible origins is that the orbits of the rings and the main body would be coplanar.
  • The problem with orbits is that unless they are coplanar with the equator, they have a nasty tendency to cross paths.
  • Orbiting the equator would not result in one eclipse per day, since the equator is not coplanar with the ecliptic.
  • The coplanar geometries are more commonly used in the x-ray experiments since they are simpler to implement.
British Dictionary definitions for coplanar


lying in the same plane: coplanar lines
Derived Forms
coplanarity, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for coplanar

1862, from co- + planar.

Online Etymology Dictionary, © 2010 Douglas Harper
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