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 Kings have failed to advance beyond the first round in seven consecutive postseasons since winning the Stanley Cup in 2014, including six first-round exits since team president Luc Robitaille took ultimate charge of hockey operations in 2017. —Greg Beacham, Los Angeles Times, 2 May 2026

In between, Altman either worked in television or for now-defunct independent operations like Cinecom, United Artists Classics, Cannon, and New World Pictures, distributors rarely in a position to give his films wide releases, abundant advertising, or substantial resources during shooting. —Jim Hemphill, IndieWire, 1 May 2026

Golden mussels, native to China and Southeastern Asia, were first detected in October 2024 by California Department of Water Resources staff who were conducting routine operations in the Port of Stockton, a CDWR spokesperson told ABC News. —Julia Jacobo, ABC News, 1 May 2026

During the operation, one firefighter suffered burns to his upper body and was transported to the hospital for evaluation. —Briauna Brown, CBS News, 1 May 2026

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