Dictionary.com
Thesaurus.com

exitance

British  
/ ˈɛksɪtəns /

noun

  1. a measure of the ability of a surface to emit radiation See luminous exitance radiant exitance

"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

Etymology

Origin of exitance

C20: from exit + -ance