bi·re·frin·gence (b??r?-fr?n?j?ns)n. The resolution or splitting of a light wave into two unequally reflected or transmitted waves by an optically anisotropic medium such as calcite or quartz. Also called double refraction.bi?re·frin?gent adj.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.birefringence (?ba?r??fr?nd??ns) n (General Physics) another name for double refraction ?bire?fringent adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014dou?ble refrac?tion n. the separation of a ray of light into two unequally refracted, plane-polarized rays of orthogonal polarizations, occurring in crystals in which the velocity of light rays is not the same in all directions. Also called birefringence. [1870?75] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.birefringencedouble refraction; the separation of light into two unequally refracted, polarized rays, as by some crystals. ? birefringent, adj.See also: Light-Ologies & -Isms. Copyright 2008 The Gale Group, Inc. All rights reserved.