monochord Hear it!

monochord Definition

mono·chord (män′ə kôrd′)

noun

an acoustical instrument consisting of a wooden sounding box with a single string and a movable bridge set on a graduated scale: used for determining musical intervals mathematically by dividing the string into separate parts whose vibrations can be measured

Etymology: ME monocorde < MFr < LL monochordon < Gr: see mono- & chord