Source : Webster's Revised Unabridged Dictionary (1913)

Sea crawfish \Sea" craw"fish`\ Sea crayfish \Sea" cray"fish`\
   (Zo["o]l.)
   Any crustacean of the genus {Palinurus} and allied genera, as
   the European spiny lobster ({P. vulgaris}), which is much
   used as an article of food. See {Lobster}.

Source : WordNet®

sea crawfish
     n : large edible marine crustacean having a spiny carapace but
         lacking the large pincers of true lobsters [syn: {spiny
         lobster}, {langouste}, {rock lobster}, {crawfish}, {crayfish}]