A musical part or section higher than tenor and lower than soprano, formerly the part that performed a countermelody above the tenor or main melody.
A person or musical instrument that performs the alto part.
An alto saxophone
The lowest female voice or voice part, falling between tenor and mezzo-soprano. The terms contralto and alto refer to a similar musical pitch, but among singers, the term contralto is reserved for female singers; the equivalent male form is counter-tenor. Originally the contratenor altus was a high countermelody sung against the tenor or main melody.