MODE OF OPERATION can be defined as the way in which a SYSTEM or machine operates. It is the set of procedures and processes that are used to control the functioning of a SYSTEM. The crossword solution for this term is SYSTEM, which is a 6 letter word. SYSTEM is an organized set of components that work together to achieve a common goal. It can refer to a physical SYSTEM, such as a computer, or a conceptual SYSTEM, such as a business.