Source : Webster's Revised Unabridged Dictionary (1913)

Crawfish \Craw"fish`\ (kr[add]"f[i^]sh`), Crayfish \Cray"fish`\
   (kr[=a]"f[i^]sh`), n.; pl. {-fishes} or {-fish}. [Corrupted
   fr. OE. crevis, creves, OF. crevice, F. ['e]crevisse, fr.
   OHG. krebiz crab, G. krebs. See {Crab}. The ending -fish
   arose from confusion with E. fish.] (Zo["o]l.)
   Any crustacean of the family {Astacid[ae]}, resembling the
   lobster, but smaller, and found in fresh waters. Crawfishes
   are esteemed very delicate food both in Europe and America.
   The North American species are numerous and mostly belong to
   the genus {Cambarus}. The blind crawfish of the Mammoth Cave
   is {Cambarus pellucidus}. The common European species is
   {Astacus fluviatilis}.