"Violoncellist" Natural Recordings by Native Speakers
A person who plays the violoncello, a large-sized stringed musical instrument that is closely related to the cello and the double bass.
Here are 5 usage examples for the word "violinist" (note: "violoncellist" is not a commonly used term, but I assume you meant "violinist" which refers to a person who plays the cello is a "cellist", so I will provide examples for "violinist" and "cellist"):
A violist is a musician who plays the viola, a string musical instrument in the violin family. The viola has a slightly deeper tone and is typically tuned to a lower pitch than the violin. Violaists often provide a rich, melodic sound in a variety of musical genres, including classical, folk, jazz, and avant-garde music.