1 of 2


: an imperfection or abnormality that impairs quality, function, or utility : shortcoming, flaw
carefully inspect a tire for defects
examined the porcelain for defects
a moral defect in his nature
neural tube defects
defects of metabolism
chemistry : an imperfection (such as a vacancy or an unlike atom) in a crystal lattice (see lattice sense 2)


2 of 2


de·​fect di-ˈfekt How to pronounce defect (audio)
defected; defecting; defects

intransitive verb

: to forsake one cause, party, or nation for another often because of a change in ideology
a former KGB agent who defected to America
: to leave one situation (such as a job) often to go over to a rival
the reporter defected to another network
defector noun

Example Sentences

Noun They examine their products for defects. She was born with a heart defect. Vanity and pride were his two worst character defects. Verb 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. See More
Recent Examples on the Web
The exact causes of this condition aren’t known, but it may be associated with a defect in the protective lining (epithelium) of the bladder, an autoimmune reaction, infection, or allergy. Women's Health, 22 Mar. 2023 The two companies have defended the lack engine immobilizers by arguing they are not required by the Federal Motor Vehicle Safety Standards and therefore there is no defect with the vehicles’ security design. Elliot Hughes, Journal Sentinel, 20 Mar. 2023 But Bridges had been born with a common genetic heart defect: aortic valve stenosis, a mutation of the valve in the heart’s main artery, the aorta. Sandee Lamotte, CNN, 5 Mar. 2023 This defect, however, does not arise from flaws in the court’s design. WSJ, 28 Feb. 2023 According to research published in the journal PLoS Pathogens, people with dandruff may have a skin barrier defect that’s aggravated by Malassezia. Lisa Bain, Good Housekeeping, 28 Feb. 2023 Ford Motor’s battery supplier says the defect that led to a fire in an electric F-150 Lightning and halted production earlier this month is not a fundamental flaw in the design of the power source. Bykeith Naughton And Bloomberg, Fortune, 27 Feb. 2023 The genetic defect that causes cystic fibrosis is most common in people of Northern European ancestry, as are the specific mutations needed for Trikafta to work. Rebecca Robbins, New York Times, 7 Feb. 2023 In a statement to the CPSC, Cosori explained that their own investigation turned up a potential defect in the electrical wiring of the appliances, resulting in potential fire and injury risks. Zee Krstic, Good Housekeeping, 24 Feb. 2023
During the late stages of the Korean War, the Air Force had dropped leaflets over North Korea offering a $100,000 reward to the first North Korean pilot to defect with a MIG. Richard Goldstein, New York Times, 6 Jan. 2023 González’s father, a waiter who had received invitations to defect while in the United States, was appointed to the island’s National Assembly but later stepped down without any official explanation. Patrick Oppmann, CNN, 6 Feb. 2023 Konstantin Yefremov, the most senior Russian soldier to defect and speak out openly against the war, is now in hiding and spoke to ABC News from Mexico. Patrick Reevell, ABC News, 5 Feb. 2023 But now, even a Democratic member could make the motion to vacate, and if the entire Democratic caucus supports it, given the slim GOP margin in the House, only four Republicans would have to defect in order to fire McCarthy. Stanley M. Brand, The Conversation, 20 Jan. 2023 Yet in Cuba, whose top boxers and baseball players often defect in search of professional paydays, money also matters. New York Times, 30 May 2022 That narrow margin gives the hard right more power; only five have to defect to defeat leadership initiatives – and McCarthy found out during the speaker election circus that may haunt his term. David Jackson, USA TODAY, 12 Jan. 2023 If more Republicans defect, McCarthy’s climb to speakership will grow even steeper. Staff Writer Follow, Los Angeles Times, 4 Jan. 2023 As the group's membership dwindled before the cult was ultimately shut down, the Leonard brothers announced their plans to defect, according to Ross. Chris Harris, Peoplemag, 1 Dec. 2022 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'defect.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History



Middle English, borrowed from Latin dēfectus "failure, absence, lack, weakness," from dēficere "to be lacking, run short, weaken, fail" + -tus, suffix of action nouns — more at deficient


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


15th century, in the meaning defined at sense 1


1596, in the meaning defined at sense 1

Time Traveler
The first known use of defect was in the 15th century

Dictionary Entries Near defect

Cite this Entry

“Defect.” Dictionary, Merriam-Webster, Accessed 1 Apr. 2023.

Kids Definition


1 of 2 noun
: a lack of something necessary for completeness or perfection


2 of 2 verb
de·​fect di-ˈfekt How to pronounce defect (audio)
: to desert a cause or party often in order to take up another
defector noun

Medical Definition


de·​fect ˈdē-ˌfekt How to pronounce defect (audio) di-ˈ How to pronounce defect (audio)
: a lack or deficiency of something necessary for adequacy in form or function
a hearing defect

Legal Definition


: something or a lack of something that results in incompleteness, inadequacy, or imperfection: as
: a flaw in something (as a product) especially that creates an unreasonable risk of harm in its normal use see also latent defect
: an error or omission in a court document (as an indictment or pleading)
: some imperfection in the chain of title to property that makes the title unmarketable
defective adjective
defectively adverb
defectiveness noun

More from Merriam-Webster on defect

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