Una Corda Definition

o͝onə kôrdə

adjective

With the soft pedal depressed.

Webster's New World

adverb

(music) 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 one string rather than three.

Wiktionary

Origin of Una Corda

Italian una one corda string (so called because depressing the soft pedal causes only one string to be struck of the two or three provided for each note)

From American Heritage Dictionary of the English Language, 5th Edition