mo·dus op·er·an·di 
(mō′dəs ŏp′ə-răndē, -dī′)
(mō′dəs ŏp′ə-răndē, -dī′)n. pl. mo·di operandi (mō′dē, -dī) Abbr. MO
1. A method of operating or functioning.
2. A person's manner of working.
[New Latin modus operandī : Latin modus, mode + Latin operandī, genitive sing. gerund of operārī, to work.]