castrato

/kæsˈtrɑː.təʊ/

From Italian castrato, from Latin castrō (“to castrate”), likely from caedō (“to cut”).

1A male who has been castrated, especially a male whose testicles have been removed before puberty in order to retain his boyish voice.
2(music) A male soprano or alto voice produced by castration of the treble singer before puberty, intended to conserve his voice; the singer.