Bartolomeo Cristofori was a master Harpsichord builder, he saw his design for the Piano as the solution to the volume and dynamics issues. What made his design special was the “Action” or mechanism he devised for the strings to be struck by a hammer with a force relative to the force applied to the key.
A Bartolomeo Cristofori Piano Circa 1720
The name was originally “un cimbalo di cipresso di piano e forte” which translates to “a keyboard of cypress with soft and loud”. Over time this name became shortened to “PianoForte” and ultimately just “Piano”. With this history, you can see why a Piano is classified a “Keyed Zither”. Because the strings are struck with a hammer, the Piano is also considered a “Stringed Percussion” instrument.
A Stodart Grand Piano Made in London, 1795