defect

verb

de·​fect di-ˈfekt 

defected; defecting; defects

intransitive verb

1

: to forsake one cause, party, or nation for another often because of a change in ideology

a former KGB agent who defected to America

2

: to leave one situation (such as a job) often to go over to a rival

the reporter defected to another network

defector

di-ˈfek-tər 

noun

Synonyms of defect

• desert
• abandon
• reject
• go back on
• cut off

Examples of defect in a Sentence

The Russian scholar defected in 1979.

She defected from the conservative party.

He defected to the West before the war began.

The reporter defected to another TV network.

Recent Examples on the Web

Palantir solved the prisoner’s dilemma by defecting first. —Michael Gregory, The Conversation, 4 June 2026

There also is the issue of players who defected to LIV Golf, a rival league that has its own set of issues now that the Public Investment Fund of Saudi Arabia will stop paying for it after this year. —ABC News, 3 June 2026

Anthropic was founded in 2021 by a group of executives and researchers who defected from OpenAI over concerns about the company's direction. —Ashley Capoot, CNBC, 1 June 2026

Both Geyser and Weier were later found not guilty by reason of mental disease or defect and were sentenced to a maximum of 25 to 40 years in a psychiatric facility. —Caroline Blair, PEOPLE, 31 May 2026

Word History

Etymology

borrowed from Latin dēfectus, past participle of dēficere "to be lacking, fail, become disaffected, go over (to the side of an opponent)" — more at deficient

First Known Use

1596, in the meaning defined at sense 1

Phrases Containing defect

• birth defect

Kids Definition

defect

1 of 2 noun

de·​fect ˈdē-ˌfekt  di-ˈfekt 

: a lack of something necessary for completeness or perfection

defect

2 of 2 verb

de·​fect di-ˈfekt 

: to desert a cause or party often in order to take up another

defection

-ˈfek-shən

noun

defector

-ˈfek-tər 

noun

Medical Definition

defect

noun

de·​fect ˈdē-ˌfekt  di-ˈ 

: a lack or deficiency of something necessary for adequacy in form or function

a hearing defect

Legal Definition

defect

noun

de·​fect ˈdē-ˌfekt, di-ˈfekt 

: something or a lack of something that results in incompleteness, inadequacy, or imperfection: as

a

: a flaw in something (as a product) especially that creates an unreasonable risk of harm in its normal use see also latent defect

b

: an error or omission in a court document (as an indictment or pleading)

c

: some imperfection in the chain of title to property that makes the title unmarketable

defective

di-ˈfek-tiv 

adjective

defectively adverb

defectiveness noun