Definition of altos:
(n) :
A person or musical instrument that performs the alto part.
(n) :
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.
(n) :
(colloquial, music) An alto saxophone.
(n) :
A census-designated place in Marin County, California, United States.
(n) :
A surname.
(n) :
(aerospace) initialism of air launch to orbit.