(per′ə·wing′kəl) noun
1. A small marine snail of the genus Littorina, especially the edible European periwinkle (L. littorea), now common on the east coast of the United States, or the American periwinkle (L. palliata).
2. Any of various other small univalves. [OE pinewinclan, winewinclan, pl.,? <L pinna a mussel (<Gk.) + OE wincla a shellfish;? infl. in form by PERIWINKLE²]

(per′ə·wing′kəl) noun
A plant of the genus Vinca (family Apocynaceae); especially, either of two European trailing shrubs, V. minor and V. major, with shining, evergreen, opposite leaves, and blue, or sometimes white, flowers. They are commonly called myrtle or creeping myrtle in the United States. [OE peruince <L pervinca <vinca pervinca, prob. <pervincire <per- thoroughly + vincire bind]