noun
or ban·do·ne·on banˈdōnēˌän
( -s )
Etymology: bandonion from German, from Heinrich Band, 19th century German musician, its inventor + German -on- (as in harmonika harmonica, accordion, from English harmonica ) + -ion (as in akkordion accordion); bandoneon, from Spanish bandoneón, from German bandonion — more at harmonica , accordion
: an accordion popular in So. America having buttons for both treble and bass notes with each bass button representing or sounding a single note not a chord