What does "tre corde" mean in piano music?

The term "tre corde" translates to "three strings" in Italian. In the context of piano music, it indicates that the pianist should release the soft pedal (una corda), which alters the sound by allowing the hammers to strike more strings rather than fewer. The piano produces its normal sound when "tre corde" is used, as it reflects the use of three strings per note, which is standard for many pianos.

This terminology is rooted in the mechanics of the piano. Early pianos had a mechanism where pressing the soft pedal would shift the action slightly, allowing the hammers to only strike one of the three strings per note (the una corda effect). Releasing the soft pedal restores full touch and sound, utilizing all three strings. This nuanced understanding connects the term directly to the instrument’s sound production and performance practice.