Noun
an acute disease characterized by fever and swollen lymph nodes and an abnormal increase of mononuclear leucocytes or monocytes in the bloodstream; not highly contagious; some believe it can be transmitted by kissing
Source: WordNetI don't like Heather Graham. She did an interview and said, 'I didn't want to kiss Corey; I didn't want to catch his mononucleosis. He had a kissing disease.' Corey Haim