Source : Webster's Revised Unabridged Dictionary (1913)

Rudd \Rudd\, n. [See {Rud}, n.] (Zo["o]l.)
   A fresh-water European fish of the Carp family ({Leuciscus
   erythrophthalmus}). It is about the size and shape of the
   roach, but it has the dorsal fin farther back, a stouter
   body, and red irises. Called also {redeye}, {roud},
   {finscale}, and {shallow}. A blue variety is called
   {azurine}, or {blue roach}.

Source : WordNet®

rudd
     n : European freshwater fish resembling the roach [syn: {Scardinius
         erythrophthalmus}]