A basso (or bass) is a male singer who sings in the lowest Vocal range of the human voice. A typical bass has a range extending from around the F below the bottom of the bass clef to the E above middle C (i.e. F2-E4). Bass also used to refer to a low speaking voice.
Types
In Classical music, and particularly in Opera, the following distinctions are often made among different kinds of bass voices:
Basso profondo (frequently misspelled basso profundo or French basse noble) is a particularly deep and resonant voice. It may reach the B below the bass clef, but is most distinguished by its dark and cavernous timbre. A typical role in opera is Sarastro from Mozart's Die Zauberflöte.
Basso cantante (French basse chantante) is a lighter, more lyrical voice, perhaps with a slightly higher range. A typical role in opera is Escamillo from Bizet's Carmen.
Basso buffo literally means "comic bass." It is used to describe operatic roles that do not call for lyrical, elaborate singing but do require a strong comic acting ability. A typical role in opera is Don Bartolo from Rossini's opera Il barbiere di Siviglia.
Bass-baritone is a voice with the resonant low notes of the typical bass but with the ability to sing in a baritonal Tessitura. Sometimes it also refers to a voice with a range and tone somewhere between a bass and a Baritone. A typical role in opera is Wotan from Wagner's Der Ring des Nibelungen.