Violone
The violone (pronounced: "Vee-o-LOH-ne") is a very big string instrument that used to be used in the 16th and 17th centuries.  It is like a double bass, but it belongs to the viol family.  The name "violone" means "large viol".  It was really a "double-bass viola da gamba".  It usually had six strings, and the fingerboard had frets (like a guitar) which showed where to put the fingers of the left hand to make the notes.  The bow was held underhand (with the palm of the hand facing up).