Meaning

noun tiny lobster-like crustaceans usually boiled briefly

noun small freshwater decapod crustacean that resembles a lobster

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

origin1620s, folk etymology from Middle English crevis, from Old French crevice (French écrevisse), influenced by fish. Compare crayfish.

Etymology from Wiktionary, CC BY-SA 3.0