Толковый словарь английского языка Oxford English Reference - operation

n. 1 a the action or process or method of working or operating. b the state of being active or functioning (not yet in operation). c the scope or range of effectiveness of a thing's activity. 2 an active process; a discharge of a function (the operation of breathing). 3 a piece of work, esp. one in a series (often in pl.: begin operations). 4 an act of surgery performed on a patient. 5 a a strategic movement of troops, ships, etc. for military action. b preceding a code-name (Operation Overlord). 6 a financial transaction. 7 Math. the subjection of a number or quantity or function to a process affecting its value or form, e.g. multiplication, differentiation. Phrases and idioms operations research = operational research. Etymology: ME f. OF f. L operatio -onis (as OPERATE)