Ossia

An unusual use of ossia is found in Alban Berg`s Violin Concerto where several ossia parts are included for the solo violin. If the soloist chooses to play these, the concertmaster is required to play a different ossia (which takes part of the solo violin line that is lost in favor of the soloist`s ossia). ...
Found on http://en.wikipedia.org/wiki/Ossia

ossia

alternatively; rather (in music)
Found on http://phrontistery.info/o.html

ossia

ossia
Found on http://www.musictheory.org.uk/res-musical-terms/italian-musical-terms.php
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