Answer:
The word virtuoso (from latin virtuosus) is an Italian word meaning in English "an individual who possesses outstanding excellence" in any specified field.
Thus virtuoso violinist simply means somebody who is a performer of outstanding excellence on the violin such as the great Paganini.
The term would normally only be used today to refer to a violinist who is a star performer such as being a brilliant soloist in a great concert performance of a Concerto for violin and orchestra or in chamber music, rather than to describe all or any of the first or second violinists playing in a symphony orchestra.
simply put. it is a extremely talented violinist.