plectr- +

(Greek plektron > Latin plectrum: thing to strike with; such as, a pick for a lyre, a zither, a guitar, an autoharp, etc.)

auscultoplectrum
An instrument for use in both auscultation and percussion of bodily examinations.
plectron
1. The hammer form assumed by certain bacilli during sporulation.
2. A small thin device (of metal, plastic, or ivory) used to pluck a stringed instrument.
plectrum (s), plectra (pl)
1. A small flat pointed piece of plastic, or other material; used for plucking or strumming the strings of a guitar or similar instrument.
2. A small thin piece of metal, plastic, bone, or similar material, used to pluck the strings of certain instruments, such as the zither or lute.
zither
1. A musical instrument with strings stretched over a flat sounding box; it is laid flat and played with a plectrum and with fingers.
2. Etymology: from Greek kithara, Latin cithara, Old High German zitara, and German Zither.

Quitar is from about 1621, and is ultimately from Greek kithara, and Latin cithara; a stringed musical instrument related to the lyre, perhaps from Persian sihtar, "sitar".

The name, "guitar", reached England several times, including early in the 14th century as giterne, in reference to various stringed, guitar-like, instruments. The modern word is directly from Spanish guittara, which came from Arabic qitar, and from the Greek kithara.