a singer whose voice lies in the alto clef
"The choir director assigned the solo part to an alto, noting that her comfortable range aligned perfectly with the notes written in the alto clef."
the highest adult male singing voice
"The tenor soloist sang in harmony with the alto section during the church choir performance."
(of a musical instrument) the second highest instrument in a family of musical instruments
"The alto saxophone sits between the soprano and tenor saxes as the second highest instrument in that family."
the pitch range of the lowest female voice
"The alto sang the soaring melody in the lower register of the choir."
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.
"The alto sang the graceful countermelody weaving above the deep tenor line during the Renaissance motet."
In plain English: An alto is a type of musical instrument that produces lower-pitched sounds than other woodwinds but higher ones than brass instruments.
"The alto sang the lead part in our choir's performance today."
Usage: In modern music, an alto refers to a female voice range between mezzo-soprano and contralto or a male counter-tenor singing in falsetto. This term specifically denotes the vocal register itself rather than describing someone's general height compared to others.
of or being the highest male voice; having a range above that of tenor
"The choir director assigned the boy soprano to sing the alto part because his voice had the necessary high range."
A surname.
"The famous composer George Frederic Handel was sometimes referred to by his surname Alto in early family records, though it is more commonly known as a musical term."
The word alto comes directly from Italian, where it means "high." It entered English as a musical term describing the high range of voices or instruments.