Source : Webster's Revised Unabridged Dictionary (1913)

Pickerel \Pick"er*el\, n. [Dim. of {Pike}.] [Written also
   {pickerell}.]
   1. A young or small pike. [Obs.]

            Bet [better] is, quoth he, a pike than a pickerel.
                                                  --Chaucer.

   2. (Zo["o]l.)
      (a) Any one of several species of freshwater fishes of the
          genus {Esox}, esp. the smaller species.
      (b) The glasseye, or wall-eyed pike. See {Wall-eye}.

   Note: The federation, or chain, pickerel ({Esox reticulatus})
         and the brook pickerel ({E. Americanus}) are the most
         common American species. They are used for food, and
         are noted for their voracity. About the Great Lakes the
         pike is called pickerel.

   {Pickerel weed} (Bot.), a blue-flowered aquatic plant
      ({Pontederia cordata}) having large arrow-shaped leaves.
      So called because common in slow-moving waters where
      pickerel are often found.

Source : WordNet®

pickerel weed
     n : American plant having spikes of blue flowers and growing in
         shallow water of streams and ponds [syn: {pickerelweed},
         {wampee}, {Pontederia cordata}]