Dreis·se·na prop. n. Zool. A genus of bivalve shells of which one species (Dreissena polymorpha) is often so abundant as to be very troublesome in the fresh waters of Europe.
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Dreissena polymorpha
n : inch-long mollusk imported accidentally from Europe; clogs
utility inlet pipes and feeds on edible freshwater
mussels [syn: zebra mussel]