operation

noun

op·​er·​a·​tion ˌä-pə-ˈrā-shən 

1

: performance of a practical work or of something involving the practical application of principles or processes

Practice until you can go through the whole operation without hesitation or thinking.

2

a

: an exertion of power or influence

the operation of a drug

b

: the quality or state of being functional or operative

The plant is now in operation.

c

: a method or manner of functioning

a machine of very simple operation

3

: efficacy, potency

—archaic except in legal usage

4

: a procedure performed on a living body usually with instruments especially for the repair of damage or defect or the restoration of health

needed an operation to remove his appendix

5

: any of various mathematical or logical processes (such as addition) of deriving one entity from others according to a rule

Multiplication is one mathematical operation.

6

a

: a usually military action, mission, or maneuver including its planning and execution

military operations for a large-scale invasion

b

operations plural : the office on the flight line of an airfield where pilots file clearance for flights and where flying from the field is controlled

c

operations plural : the agency of an organization charged with carrying on the principal planning and operating functions of a headquarters and its subordinate units

7

: a business transaction especially when speculative

continued his operations in cotton futures

8

: a single step performed by a computer in the execution of a program (see program entry 1 sense 6a)

9

: a usually small business or establishment

ran a struggling operation

Synonyms of operation

• mission
• job
• assignment
• duty

Examples of operation in a Sentence

The family runs a small farming operation.

The company is a billion-dollar operation.

Recent Examples on the Web

The 35-year-old was arrested on November 6 in a joint operation between the FBI and Thai authorities, one week after entering the country on a flight to Phuket, according to Thailand’s Cyber Crime Investigation Bureau (CCIB). —Helen Regan, CNN Money, 15 Nov. 2025

The Federal Bureau of Investigations revealed on Friday that 15 people from the Kansas City area were arrested on child-exploitation charges over the summer as part of a three-month-long operation. —Caroline Zimmerman, Kansas City Star, 15 Nov. 2025

Conduent claims that its investigation found no ongoing malicious activity and said operations were safely restored after the breach was contained. —Kurt Knutsson, FOXNews.com, 14 Nov. 2025

As operations return to normal, CLT said some delays may continue. —Chase Jordan updated November 14, Charlotte Observer, 14 Nov. 2025

Word History

Etymology

Middle English operacion "work, action, procedure performed on a body, functioning," borrowed from Medieval Latin operātiōn-, operātiō, going back to Latin, "application of effort, functioning (of natural forces)," from operārī "to busy oneself, be at work" + -tiōn-, -tiō, suffix of action nouns — more at operate

First Known Use

14th century, in the meaning defined at sense 1

Phrases Containing operation

• sex change operation

Rhymes for operation

• abdication
• aberration
• abjuration
• abnegation
• abrogation
• acceptation
• acclamation
• acclimation
• accusation
• activation
• actuation
• acylation

Kids Definition

operation

noun

op·​er·​a·​tion ˌäp-ə-ˈrā-shən 

1

: the act, process, method, or result of operating

does the whole operation without stopping

the operation of a drug

2

: the quality or state of being able to work or function

put a factory into operation

3

: a procedure performed on a living body usually with medical instruments especially to restore health or repair damage or defect

4

: a mathematical or logical process (as addition or multiplication) for getting one mathematical expression from others according to a rule

5

: the process of putting military or naval forces into action

6

: a single step in a computer program

7

: a usually small business or establishment

Medical Definition

operation

noun

op·​er·​a·​tion ˌäp-ə-ˈrā-shən 

: a procedure performed on a living body usually with instruments for the repair of damage or the restoration of health and especially one that involves incision, excision, or suturing