1. the state of being in effect or being operative

- that rule is no longer in operation

Definition categories: state, action, activeness, activity

2. a business especially one run on a large scale

- a large-scale farming operation

- a multinational operation

- they paid taxes on every stage of the operation

Definition categories: act

3. a planned activity involving many people performing various actions

- they organized a rescue operation

- the biggest police operation in French history

- running a restaurant is quite an operation

Definition categories: act, activity

4. (computer science) data processing in which the result is completely specified by a rule (especially the processing that results from a single instruction)

- it can perform millions of operations per second

Definition categories: process

5. activity by a military or naval force (as a maneuver or campaign)

- it was a joint operation of the navy and air force

Definition categories: act, activity

6. a medical procedure involving an incision with instruments; performed to repair damage or arrest disease in a living body

- they will schedule the operation as soon as an operating room is available

Similar word(s): surgery

Definition categories: act

7. a process or series of acts especially of a practical or mechanical nature involved in a particular form of work

- the operations in building a house

- certain machine tool operations

Similar word(s): procedure

Definition categories: act, work

8. process or manner of functioning or operating

- the power of its engine determines its operation

- the plane's operation in high winds

Similar word(s): functioning, performance

Definition categories: process

9. (psychology) the performance of some composite cognitive activity; an operation that affects mental contents

- the cognitive operation of remembering

Similar word(s): process

Definition categories: thought, cognition, knowledge, noesis

10. (mathematics) calculation by mathematical methods

- they were learning the basic operations of arithmetic

Definition categories: act, calculation, computation, computing

11. the activity of operating something (a machine or business etc.)

- her smooth operation of the vehicle gave us a surprisingly comfortable ride

Definition categories: act, activity

Sentences with operation as a noun:

- It is dangerous to look at the beam of a laser while it is in operation.

- The police ran an operation to get vagrants off the streets.

- The Katrina relief operation was considered botched.

- We run our operation from a storefront.

- They run a multinational produce-supply operation.

- She had an operation to remove her appendix.