A cellist is a person who plays the cello — the large string instrument that sits on the floor, held between the player’s knees. It sounds lower and warmer than a violin. A cellist may play in an orchestra, in a small group, or alone. The word is simply “cello player” in one piece: cello + -ist. Though actually, cello itself is a short form of the Italian name violoncello. The first sound is like “chell,” not like the “s” in city, and not like a prison cell.