una corda

Meanings

1. In piano music, the notation indicating that the player depresses the soft pedal, altering, and reducing the volume of the sound. In many pianos, this results in the hammer striking two strings rather than three as in tre corde. Originally, it would have struck one string, but modern pianos have their strings too close together to achieve a true una corda - the movement of the hammers would result in also hitting the first string of the next note.

Etymology

From Italian una corda (“one string”).