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defect

American  
[dee-fekt, dih-fekt, dih-fekt] / ˈdi fɛkt, dɪˈfɛkt, dɪˈfɛkt /

noun

  • defects
    plural
  1. a shortcoming, fault, or imperfection: a defect in a machine.

    a defect in an argument;

    a defect in a machine.

  2. lack or want, especially of something essential to perfection or completeness; deficiency: a defect of action.

    a defect of common sense

    a defect of action.

  3. Also called lattice defect, crystal defect. Crystallography. a discontinuity in the lattice of a crystal caused by missing or extra atoms or ions, or by dislocations.


verb (used without object)

  • defects,
    present (3rd person singular)
  • defected,
    past participle,  past
  • defecting
    present participle
  1. to desert a cause, country, etc., especially in order to adopt another (often followed by from orto ).

    He defected from the U.S.S.R. to the West.

defect British  

noun

  1. a lack of something necessary for completeness or perfection; shortcoming; deficiency

  2. an imperfection, failing, or blemish

  3. crystallog a local deviation from regularity in the crystal lattice of a solid See also point defect dislocation

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

verb

  1. (intr) to desert one's country, cause, allegiance, etc, esp in order to join the opposing forces

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Synonym Usage

Defect, blemish, flaw refer to faults that detract from perfection. Defect is the general word for any kind of shortcoming or imperfection, whether literal or figurative: a defect in eyesight, in a plan. A blemish is usually a defect on a surface, which mars the appearance: a blemish on her cheek. Flaw is applied to a defect in quality, caused by imperfect structure (as in a diamond) or brought about during manufacture (as in texture of cloth, in clearness of glass, etc.).

Other Word Forms

Derived Forms

Inflected Forms

Nouns

Participles

Conjugated Forms

Present

Past

Future


Etymology

Origin of defect

First recorded in 1375–1425; late Middle English, from Latin dēfectus “failure, weakness,” equivalent to dēfec-, variant stem of dēficere “to run short, fail, weaken” ( see deficient) + -tus suffix of verb action


Explanation

A flaw in something is a defect. At certain stores you can buy clothes with slight defects. You have to be careful because the defect can be minor, like a missing button, or major, like sleeves of uneven lengths. In a person, a defect is an imperfection, which can manifest itself mentally or physically. If you are diagnosed with a heart defect, you will have to seek the advice of specialists. A hearing defect might leave your dad deaf in one ear. If you are becoming forgetful, you can joke that you are developing a mental defect, but if it continues, you'll probably want to have your head examined.

Keep Reading on Vocabulary.com

Vocabulary lists containing defect

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

To test their approach, the researchers first examined a nitrogen-vacancy center in diamond, a type of crystal defect widely studied for quantum applications.

From Science Daily ● Oct. 23, 2026

Both indictments were later dismissed because of a defect involving the appointment of the prosecutor, although the Justice Department subsequently pursued a new indictment against Comey.

From Salon ● Oct. 17, 2026

The law firm claimed he “struck a defect in the roadway causing him to fall.”

From The Wall Street Journal ● Oct. 6, 2026

"The pilots remain in control of the airplane," Bedford said of the new software defect.

From Barron's ● Sep. 28, 2026

“There is, I believe, in every disposition a tendency to some particular evil—a natural defect, which not even the best education can overcome.”

From "Pride and Prejudice" by Jane Austen

As long as they adhere to price caps, agree to certain labor requirements and fix repairs that arise, they’re protected from lawsuits from buyers concerning defects 10 years after construction of the home.

From Los Angeles Times ● Oct. 24, 2026

"We provided the missing piece of the puzzle needed to completely describe the optical cycle of spin defects," Galli said.

From Science Daily ● Oct. 23, 2026

"The new derivation came together after years of work on the optical cycle of spin defects."

From Science Daily ● Oct. 23, 2026

While it doesn’t offer insurance, all jewelry does come with a warranty that covers “imperfections that are the result of defects in the manufacturing process.”

From MarketWatch ● Oct. 22, 2026

I thought of Mother, and of the many times she’d told me that antibiotics poison the body, that they cause infertility and birth defects.

From "Educated" by Tara Westover

Reform MSP Graham Simpson did not resign when he defected from the Scottish Conservatives in August 2025.

From BBC ● Oct. 20, 2026

Sarah Cooper-Lesadd, who defected to Plaid Cymru last month, also said she was "not surprised" by recent allegations of sexism and misogyny within the party, claiming she had personal experience of such behaviour.

From BBC ● Oct. 17, 2026

Several lawmakers from across the political spectrum have defected to the Liberals in the past year.

From The Wall Street Journal ● Sep. 30, 2026

To reinvigorate demand among consumers who have defected to nimble local competitors, Sparks is touring cities to study fitness trends and dramatically expanding Nike’s local product-creation team.

From The Wall Street Journal ● Sep. 29, 2026

Philby had not yet been revealed as a Soviet spy, but two of his colleagues, Donald Maclean and Guy Burgess, had just defected to the Soviet Union.

From "Blink" by Malcolm Gladwell

These reporters joined a Reform councillor, Alan Feeney, in Solihull, in the West Midlands, where he was campaigning to retain his seat on the council, after defecting from the Conservative Party in 2025.

From BBC ● Oct. 15, 2026

Despite leaving, Tugay did not follow Ozel, saying he would remain independent, with rumours emerging over the summer that he was considering defecting to AKP -- all of which he denied.

From Barron's ● Oct. 7, 2026

Some diners have been defecting to competitors like Chick-fil-A, which are known for heavily staffed, attentive service.

From The Wall Street Journal ● Sep. 11, 2026

At the dinner, I tried to get a sense if there were more women like Smith—sweet, older Christian Alabamians—snapping and defecting to the left.

From Slate ● May 4, 2026

Common sense told him that telling lies and defecting from duty were sins.

From "Catch-22" by Joseph Heller

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