Fukasetsu (Zen, Japanese)

By definition, this is a state beyond description. Although attempts are made to describe the ineffable they always fall short of the reality which can only be experienced. Thus, the description of the state of having realized buddhahood and become enlightened can be recognized only by one who has experienced it - it is [fukasetsu]

(unsayable). This is similar to the statement in the Mundakya Upanishad that wisdom can be learned but not taught.