the way a particular person tends to do things

his MO isn't prescribing the solution but sparking more questions

Connor can't figure out the killer's MO

(of a disk or disk drive) magneto-optical

Medical Officer

that looks nasty—better go and see the MO

Missouri (in official postal use)

money order

a short period of time

hang on a mo!

the chemical element of atomic number 42, a brittle silver-grey metal of the transition series, used in some alloy steels

the chemical element molybdenum