'accordionist' originates from 'accordion', which comes from the German word 'Akkordeon', where 'Akkord' meant 'musical chord'.

'Akkordeon' transformed into the English word 'accordion', and eventually led to the formation of 'accordionist' to describe someone who plays the instrument.

Initially, it referred to someone who played the 'Akkordeon', and this meaning has largely remained the same in modern usage.