Qu'est-ce qu'un bass? Qu'est-ce qu'un bass? Any of several North American freshwater fishes of the family Centrarchidae, related to but larger than the sunfishes.Any of various marine fishes of the family Serranidae, such as the sea bass and the striped bass.The tones in the lowest register of an instrument. A low-pitched sound or tone.A male singing voice of the lowest range.A singer who has such a voice.An instrument that sounds within this range.A vocal or instrumental part written within this range.An instrument, especially a double bass, that produces tones in a low register.Having a deep tone.Low in pitch.