Source : Webster's Revised Unabridged Dictionary (1913)

Grindle \Grin"dle\, n. (Zo["o]l.)
   The bowfin; -- called also {Johnny Grindle}. [Local, U. S.]

Source : WordNet®

grindle
     n : primitive long-bodies carnivorous freshwater fish with a
         very long dorsal fin; found in sluggish waters of North
         America [syn: {bowfin}, {dogfish}, {Amia calva}]