A dictionary definition of “virtuoso” (which comes from the same root as “virtue”) includes any person who has exceptional technique and skill in an art form. These days the term tends to be limited to musicians.
Early on, it applied to a composer as well as a player. During the 19th century the term gained popularity referring to solo instrumentalists such as Liszt on the piano, or Paganini on the violin; forgetting that in the previous century, von Biber, (violin) Handel (organ), Domenico Scarlatti (harpsichord), Luigi Boccherini, (cello) and others had all been virtuosi on their instruments.
It was during the 19th century, however, that the virtuoso affected the history of music in not only the case of the virtuoso player/composer, but the virtuoso player causing music by another composer. A case in point is Brahms, who wrote more than one work, but notably his Violin Concerto – one of the pillars of the canon of Western music – for the virtuoso violinist Joseph Joachim; and a late flurry of works for the clarinet – also music that ranks with the best of its genre – for the virtuoso clarinettist, Richard Mühlfeld. Many great works have been created by this sort of creative partnership.