noun [with adj.] informal
a person who is enthusiastically interested in and very knowledgeable about a particular subject
a voice, instrument, or sound of the lowest range, in particular
• the lowest adult male singing voice.
• [as adj.] denoting the member of a family of instruments that is the lowest in pitch
• informal a bass guitar or double bass.
• the low-frequency output of a radio or audio system, corresponding to the bass in music