1797, from Modern Latin mollusca, chosen by Linnaeus as the name of an invertebrate order (1758), from neuter plural of Latin molluscus "thin-shelled," from mollis "soft" (see melt (v.)). Linnæus applied the word to a heterogeneous group of invertebrates, not originally including mollusks with shells; the modern scientific use is after a classification proposed 1790s by French naturalist Georges Léopole Chrétien Frédéric Dagobert, Baron Cuvier (1769-1832).
molluscum mol·lus·cum (mə-lŭs'kəm)
n. pl. mol·lus·ca (-kə)
Any of various skin diseases marked by the occurrence of soft spherical tumors on the face or the body.