n.

1. 操作；運轉[U]
   The operation of this machine is simple.

   這個機器的操作很簡單。

2. 經營；營運[U]
   The operation of a railroad needs many men.

   鐵路的營運需要很多人。

3. 作用；效力[U][C]
   The operation of natural law is constant.

   自然法則的作用是永恆的。

4. 活動；工作；事[C][P1]
   The rescue operation lasted three days.

   救援活動持續了三天。

5. 【醫】手術[C][（+on/for）]
   Her father underwent a major operation last week.

   她父親上週動了一次大手術。

6. 軍事行動，作戰[C][P1]
   The general was in command of operations in the north.

   將軍負責指揮北方的作戰行動。

7. 交易，買賣[C][P1]
   He continued his operations in cotton futures.

   他繼續進行棉花期貨交易。

8. 【數】運算[C]
9. （尤指法律文件的）生效[U]

n.

1. the action or process of operating.
2. an act of surgery performed on a patient.
3. an organized activity involving a number of people:
   a rescue operation.
4. a business organization; a company.
5. Mathematics  a process in which a number, quantity, expression, etc. is altered or manipulated according to set formal rules.