Definition of "Crayfish" :

noun: large edible marine crustacean having a spiny carapace but lacking the large pincers of true lobsters

noun: small freshwater decapod crustacean that resembles a lobster

noun: tiny lobster-like crustaceans usually boiled briefly

noun: warm-water lobsters without claws; those from Australia and South Africa usually marketed as frozen tails; caught also in Florida and California