What does high mono on blood test mean?

Mononucleosis: An infection where neck gland become enlarged, fever, weakness and is easily treated.

Nothing specific: The monocytes are a form of white cell, cousin to the lymphocyte, that often increases their relative number in a variety of infectious conditions. Mononucleosis is a lay term for the elevation when it occurs with an EB virus infection.Other viruses and some bacteria can trigger the same relative increase in monocytes.