pec·ti·na·cea \ˌpektəˈnāshēə\noun plural Usage: capitalized Etymology: New Latin, from Pectin-, Pecten, type genus + -acea : a suborder of Filibranchia comprising active bivalve mollusks that have a fan-shaped shell and no siphons including the typical pectens and related forms • pec·ti·na·cean\ˌpektəˈnäsh(ē)ən\noun-s