Noun
bass saxophone (plural bass saxophones)
A member of the saxophone family of woodwind instruments that is smaller than the contrabass saxophone but larger than the baritone saxophone, with a range of A♭1 to E♭4 or similar.
A bass saxophone in B is called for in some concert band music (especially music by Percy Grainger ). Source: Internet
In earlier periods of jazz, a bass saxophone was used as a bass line instrument, though this is far less common today. Source: Internet
Often a second alto may be substituted for the soprano part (AATB) or a bass saxophone may be substituted for the baritone. Source: Internet