I know that mononucleosis is caused by ebv, but is there a such thing as a "mono cell"?

Yes: No relation between mono cell and mono disease. Mon cell is a type of white cell which fight infection in the body. Mononucleosis is caused by ebv and many other viruses.

Yes: What you be referring to is the downey cell, the atypical lymphocyte found in the blood of patients with mononucleosis, especially when related to ebv. There is also a cell called a monocyte in the blood, but no relationship to mononucleosis itself.

Confusing words: A "mono cell" is just a specialized white blood cell(monocyte) closely related to lymphocytes. It tends to show up in a greater percentage relative to other white cells in some viral infections, including EB virus mononucleosis. In a way, it is the bodies signal that this is "mono" and the term caught on as easier to remember than Epstein Barr virus infection.