1. Relating to or composed of right angles.
2. Mathematics.
   1. Of or relating to a matrix whose transpose equals its inverse.
   2. Of or relating to a linear transformation that preserves the length of vectors.

[From Greek orthogōnios : ortho-, ortho- + gōniā, angle.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.