Source : Webster's Revised Unabridged Dictionary (1913)

Puissant \Pu"is*sant\, a. [F., originally, a p. pr. formed fr.
   L. posse to be able: cf. L. potens powerful. See {Potent}.]
   Powerful; strong; mighty; forcible; as, a puissant prince or
   empire. `` Puissant deeds.'' --Milton.

         Of puissant nations which the world possessed.
                                                  --Spenser.

         And worldlings in it are less merciful, And more
         puissant.                                --Mrs.
                                                  Browning.

Source : WordNet®

puissant
     adj : powerful