The name could be of several different etymologies depending on the source of the bearer. In Nothern Europe, it is a contracted form of Monika or any name that contains the element -mona. 

In the case of the Mona Lisa, mona is an archaic Italian title, being a contraction of madonna.

It has been suggested that the name could be from the Greek monos (one) and it can also be used as an anglicized form of the Gaelic, Muadhnait (little noble one).

The name is used throughout the Middle East, in this case it is derived from the Arabic منى (muna) meaning, “wishes; desires.”

Currently, Mona is the 160th most popular female name in Germany, (2011).