noun, plural ko·ans, ko·an. Zen.
a nonsensical or paradoxical question to a student for which an answer is demanded, the stress of meditation on the question often being illuminating.
Origin of koan
1945–50; < Japanese kōan, earlier koũ-an < Middle Chinese, equivalent to Chinese gōngàn public proposal
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
(in Zen Buddhism) a problem or riddle that admits no logical solution
Word Origin for koan
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
Zen paradox, 1946, from Japanese ko "public" + an "matter for thought."
Online Etymology Dictionary, © 2010 Douglas Harper