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all'ottava

British  
/ æləˈtɑːvə /

adjective

  1.  8vamusic to be played an octave higher or lower than written

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of all'ottava

Italian: at the octave