Violone

The term violone (literally "large viol" in Italian, "-one" being the augmentative suffix) can refer to several distinct large, bowed musical instruments which belong to either the viol or violin family. The violone is sometimes a fretted instrument, and may have six, five, four, or even only three strings. The violone is also not always a contrabass instrument. In modern parlance, one usually tries to clarify the 'type' of violone by adding a qualifier based on the tuning (such as "G violone" or "D violone") or on geography (such as "Viennese violone"), or by using other terms that have a more precise connotation (such as "bass violin" or "violoncello" or "bass viol"). The term violone may be used correctly to describe many different instruments, yet distinguishing among these types can be difficult, especially for those not familiar with the historical instruments of the viol and violin families and their respective variations in tuning.

Read more about Violone:  Usage, Types of Violoni, History, Terminology