ETYM Italian alto high, from Latin altus. Related to Alt.
1. A singer whose voice lies in the alto clef.
2. The pitch range of the lowest female voice.
Voice or instrument between tenor and soprano, of approximate range G3–D5. The traditional male alto voice of early opera, also known as countertenor, is trumpetlike and penetrating; the low-register female contralto (“contra-alto”), exemplified by English singer Kathleen Ferrier, is rich and mellow in tone. Alto is also the French name for the viola.