The Collaborative International Dictionary of English v.0.48:
Sea louse \Sea" louse`\ (Zool.) Any one of numerous species of isopod crustaceans of Cymothoa, Livoneca, and allied genera, mostly parasites on fishes. [1913 Webster]WordNet (r) 3.0 (2006):
sea louse n 1: marine isopod crustacean [syn: sea louse, sea slater]