per·i·win·kle 2 
(pĕrĭ-wĭng′kəl)
(pĕrĭ-wĭng′kəl)n.
1. Any of several shrubby, trailing, evergreen plants of the genus Vinca, especially V. minor, having glossy, dark green, opposite leaves and flowers with a blue, funnel-shaped corolla.
2. Any of several erect herbs of the genus Catharanthus, especially C. roseus, having flowers with a rose-pink or white salverform corolla and a closed throat.
3. A pale purplish blue.
[Middle English pervinkle, diminutive of pervinke, from Old English pervince, from Late Latin (vinca) pervinca, alteration (perhaps influenced by Latin pervincere, to conquer completely) of Latin vicapervica, perhaps originally a magical verbal formula (the use of the periwinkle in magical rituals being known later from medieval European traditions), perhaps akin to pervicus, stubborn (per-, intensive pref.; see PER- + vincere, vic-, to conquer; see VICTOR) or to vincīre, to bind together, hold fast, and vicia, vetch; see VETCH.]