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defect

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

noun

  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.  Also called 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

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.

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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.

"Our results suggest that altered metabolism is a significant contributor to Alzheimer's progression and, in addition, addressing the metabolic defect could be an important complement to approaches focused on Alzheimer's plaques and tangles," Sun said.

From Science Daily • Jun. 10, 2026

A notice from the company described the cause of the problem as a "packaging defect".

From BBC • Jun. 6, 2026

The defect was traced back to supplier production quality and to Boeing’s inability to catch it.

From Barron's • May 27, 2026

“It takes so much to litigate a construction defect, you spend more than you do to build a house,” Scherer said.

From The Wall Street Journal • May 18, 2026

The highest-ranking KGB official ever to defect to the CIA had simply walked away.

From "Spies: The Secret Showdown Between America and Russia" by Marc Favreau

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