WordNet sense 1 (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):

mononucleosis, infectious mononucleosis, glandular fever, kissing disease

WordNet sense 2 (designating sound transmission or recording or reproduction over a single channel):

monophonic, single-channel

WordNet sense 3 (relating to or having or hearing with only one ear):

monaural