A violinist was someone who was skilled at playing the violin.
In 2366, Data combined the differing styles of violinists Jascha Heifetz and Trenka Bron-Ken expertly. Jean-Luc Picard convinced him that having done so evidenced that he had not merely imitated their techniques, but created something new from them. (TNG: "The Ensigns of Command")
Later that year, Data asked Perrin whose style of the over three hundred concert violinists that he had been programmed with that she fancied. Among the many were Heifetz, Yehudi Menuhin, Grak-tay, and Tataglia. She chose Tataglia. (TNG: "Sarek")