Definition of altissimo in English:

altissimo

adjective

Music
  • Very high in pitch:

    ‘the extreme altissimo range of his horn’
    • ‘He was inclined to use a harsh altissimo register in his saxophone playing.’
    • ‘It might be helpful and quicker to work with a good private teacher who plays the altissimo register.’
    • ‘The mastering of the first altissimo octave is the most difficult, and should be done before going higher.’
    • ‘I had to play altissimo to get F# and higher.’
    • ‘Opening the F key only a little helps the altissimo notes to speak.’

Origin

Italian, superlative of alto high.

Pronunciation:

altissimo

/alˈtɪsɪməʊ/