A piano accordion is an accordion equipped with a right-hand keyboard similar to a piano or organ. Its acoustic mechanism is more that of an organ than a piano, as they are both wind instruments, but the term "piano accordion"—coined by Guido Deiro in 1910—has remained the popular nomenclature. It may be equipped with any of the available systems for the left-hand manual.

In comparison with a piano keyboard, the keys are more rounded, smaller, and lighter to the touch. These go vertically down the side, pointing inward, toward the bellows, making them accessible to only one hand while handling the accordion.[notes 1]

The bass piano accordion is a variation of a piano accordion without bass buttons and with the piano keyboard in an octave lower. They typically have around 3 octaves.