a well known instrument for opening and shutting the locks of doors, chests, bureos, and the like.

in music, a certain fundamental note, or tone, to which the whole piece, be it in concerto, sonata, cantata, &c., is accommodated, and with which it usually begins, but always ends.

KEYSTONE of an arch, or vault, that placed at the top or vertex of an arch, to bind the two sweeps together.