bass

: low and deep sound : the lowest range of sounds used in music — compare treble

[count] : the lowest male singing voice

also : a singer who has such a voice — compare alto, soprano, tenor

a  : a kind of guitar that usually has four strings and that makes low sounds

b  : double bass

: having or indicating a low sound or range

: a kind of fish that people catch for food — see color picture on this page