ris·soi·dae \rə̇ˈsōəˌdē, -sȯi(ˌ)dē\noun plural Usage: capitalized Etymology: New Latin, from Rissoa, type genus + -idae : a large family of marine and freshwater snails (suborder Taenioglossa) with a long snout, ciliated tentacles, and eyes on small prominences at the base of the tentacles — see rissoa