The highest adult male singing voice WordNet 3.0 & Open English WordNet

A countertenor is a type of classical male singing voice whose vocal range is equivalent to that of the female contralto or mezzo-soprano voice types, generally extending from around G3 to D5 or E5, although a sopranist may match the soprano's range of around C4 to C6. Wikipedia

High classical male singing voice Wikidata

Male singing voice far higher than the typical male vocal range. Wiktionary

Singing voice. Wiktionary (translation)