sea crawfish seac·raw·fish uncommon noun 1. large edible marine crustacean having a spiny carapace but lacking the large pincers of true lobsters Synonymsspiny lobsterlangousterock lobstercrawfishcrayfishsea crawfish Related words Broader terms lobster Parts Palinurus Part of spiny lobster WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.