monoPronunciation: /ˈmɒnəʊ/Translate mono | into German | into Italian | into Spanish Definition of mono adjective 1monophonic. 2monochrome. noun (plural monos) 1a monophonic recording. [mass noun] monophonic reproduction. 2a monochrome picture. [mass noun] monochrome reproduction. 3North Americanshort for mononucleosis. 4North Americanshort for monofilament.mono in other Oxford dictionaries Definition of mono in the US English dictionary