castrato

kastraatti, kastraattilaulaja A male who has been castrated, especially a male whose testicles have been removed before puberty in order to retain his boyish voice.
A male soprano or alto voice produced by castration of the treble singer before puberty, intended to conserve his voice; the singer.
puhekieltä Castrated; especially castrated prepubescently.
Having, using or containing the voice of a castrato (noun).
Originally composed for a castrato.

Nowadays, either women or countertenors take the castrato roles.