Source : Webster's Revised Unabridged Dictionary (1913)

Unseen \Un*seen"\, a.
   1. Not seen or discovered.

   2. Unskilled; inexperienced. [Obs.] --Clarendon.

Source : WordNet®

unseen
     adj 1: not seen or perceived; "unseen natural resources"
     2: not observed [syn: {unobserved}]
     n : a belief that there is a realm controlled by a divine spirit
         [syn: {spiritual world}]