What does "cello" mean?
The term "cello" is a shortened form of violoncello, the name given to the bowed string instrument which is between the viola and double bass in size. It is rarely referred to by its full name in the present day, where it has become practically archaic.
As far as etymology goes, "cello" is derived from the ending of the Italian "violoncello," which means "little violone". This was a larger instrument that went out of fashion around the 17th century.