Synonyms for Periwinkle (same or very similar meaning)
WordNet sense 1 (commonly cultivated Old World woody herb having large pinkish to red flowers):
Cape periwinkle, Catharanthus roseus, cayenne jasmine, Madagascar periwinkle, red periwinkle, rose periwinkle, Vinca roseaWordNet sense 2 (small edible marine snail; steamed in wine or baked):
winkleFrom the ODE community, based on WordNetadd/edit