koan

noun3

1. •
   A story about a Zen master and his student, sometimes like a riddle, other times like a fable or parable, which has become an object of Zen study, and which, when meditated upon, may unlock mechanisms in the Zen student’s mind leading to satori.
2. •
   A riddle with no solution, used to provoke reflection on the inadequacy of logical reasoning, and to lead to enlightenment.

   • Gibberish. Or else a koan that Achtfaden isn’t equipped to master, a transcendent puzzle that could lead him to some moment of light. — 1973
3. •
   A therapy technique used by Traditional Chinese medicinal physicians or medical practitioners to break a presenting patients habitual pattern of thinking that has been diagnosed as the primary cause of an illness or disease.