What does "winkle" mean?

Winkle: (a) Any periwinkle. Holland. (b) Any one of various marine spiral gastropods, esp., in the United States, either of two species of Fulgar (F. canaliculata, and F. carica). Note: These are large mollusks which often destroy large numbers of oysters by drilling their shells and sucking their blood. Sting winkle, a European spinose marine shell (Murex erinaceus). See Illust. of Murex.