​MANUAL (from manus, a hand), a clavier, or set of keys, to be played by the hands. The term is used chiefly in reference to the Organ, where the keyboards for the hands and the keyboard for the feet have, for convenience, to be distinguished by some brief and suggestive name. Clavier (from clavis, a key) simply means a keyboard, without reference to the members of the body with which it is to be played.