MO adjective 2noun 5 adjective2 •Initialism of mesio-occlusal. •Initialism of magnetooptical. noun5 •Abbreviation of Missouri: a state of the United States. •Initialism of modus operandi.The Big Man is everywhere. He knows my M.O.!!!! — 1981 •Initialism of money order. •(UK) Initialism of medical officer. •Initialism of molecular orbital.
