plec·trum 
(plĕktrəm)
(plĕktrəm)n. pl. plec·trums or plec·tra (-trə)
A small thin piece of metal, plastic, bone, or similar material, used to pluck the strings of certain instruments, such as the guitar or lute.
[Latin plēctrum, from Greek plēktron, from plēssein, plēg-, to strike; see plāk-2 in the Appendix of Indo-European roots.]