piano action
Noun
Meaning
action consisting of a system of levers that move a felt hammer to strike the strings when a key is depressed
Source: WordNetHypernyms
Examples
Cristofori's piano action was a model for the many approaches to piano actions that followed.
This shifts the entire piano action so the pianist can play music written in one key so that it sounds in a different key.
Unlike in a piano action, the tangent does not rebound from the string; rather, it stays in contact with the string as long as the key is held, acting as both the nut and as the initiator of sound.