lowest of the four parts of music. The term is derived either from the Greek word βάσις, a foundation, or from the Italian adjective basso, signifying low. Of all the parts it is the most important, as upon it the chords proper to constitute a particular harmony are determined; and hence the maxim among musicians, that when the bass is properly formed the harmony can scarcely be bad.

Basses are of different kinds. Thorough-Bass is the harmony made by the bass-viol or theorbo, continuing to play both while the voices sing and the other instruments perform their parts, and also filling up the intervals when any of the other parts stop. Counter-Bass is a second or double bass, where there are several in the same concert.

Bass-Viol, a musical instrument, of a similar form with that of a violin, but much larger. It is struck with a bow as the violin is; it has the same number of strings; and it has eight stops, which are subdivided into semitones. Its sound is grave, and has a much nobler effect in a concert than that of the violin.