Source : Webster's Revised Unabridged Dictionary (1913)

Bower \Bow"er\ (bou"[~e]r), n. [G. bauer a peasant. So called
   from the figure sometimes used for the knave in cards. See
   {Boor}.]
   One of the two highest cards in the pack commonly used in the
   game of euchre.

   {Right bower}, the knave of the trump suit, the highest card
      (except the ``Joker'') in the game.

   {Left bower}, the knave of the other suit of the same color
      as the trump, being the next to the right bower in value.
      

   {Best bower} or {Joker}, in some forms of euchre and some
      other games, an extra card sometimes added to the pack,
      which takes precedence of all others as the highest card.