Other forms: sopranos; soprani
The opera performer with the highest voice is a soprano. A soprano is usually a woman, and she can hit the high notes.
A woman who sings at the highest register is one kind of soprano, and her singing voice itself can also be called a soprano. Sometimes high-voiced male singers are described this way too, although it's more common to call them countertenors, or to describe their singing voices as falsetto. Soprano is an Italian word that means "the treble in music," or "high," from sopra, or "above."