monochord

Meanings

1. A musical instrument for experimenting with the mathematical relations of musical sounds, consisting of a single string stretched between two bridges, one or both of which can be moved, and which stand upon a graduated rule for the purpose of changing and measuring the length of the part of the string between them.
2. A stringed instrument with only one string.
3. A bass note on a piano that has a single string.

Etymology

Learned borrowing from Latin monochordon, itself borrowed from Ancient Greek μονόχορδον (monókhordon). By surface analysis, mono- + chord.