Source : Webster's Revised Unabridged Dictionary (1913)

Gnosis \Gno"sis\, n. [NL., fr. Gr. gnw^sis.] (Metaph.)
   The deeper wisdom; knowledge of spiritual truth, such as was
   claimed by the Gnostics.

Source : WordNet®

gnosis
     n : intuitive knowledge of spiritual truths; said to have been
         possessed by ancient Gnostics
     [also: {gnoses} (pl)]