defect

1 of 3

noun (1)

de·​fect ˈdē-ˌfekt How to pronounce defect (audio) di-ˈfekt How to pronounce defect (audio)
Synonyms of defect
1
: an imperfection or abnormality that impairs quality, function, or utility : shortcoming, flaw
carefully inspect a tire for defects
examined the porcelain for defects
a defect in their logic
a moral defect in his nature
neural tube defects
defects of metabolism
2
chemistry : an imperfection (such as a vacancy or an unlike atom) in a crystal lattice (see lattice sense 2)

defect

2 of 3

verb

de·​fect di-ˈfekt How to pronounce defect (audio)
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 How to pronounce defect (audio)
noun

defector

3 of 3

noun (2)

de·​fec·​tor də̇ˈfektə(r) How to pronounce defector (audio)
dēˈ-, 
ˈdēˌf-
plural -s
: one that defects (as from a party or a doctrine)

Synonyms of defect

Relevance

Noun (1)

Verb

See All Synonyms & Antonyms in Thesaurus

Examples of defect in a Sentence

Noun (1) 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.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Noun
The lawsuit said this defect helped cause Avila's death and the harm the family suffered. — Paloma Chavez, PEOPLE, 3 July 2026 As release velocity increases, defects compound faster than teams can notice. — Expert Panel®, Forbes.com, 1 July 2026
Verb
Still, there are many people that will vote on election day, some of whom were already going to vote for Mills, and some who could defect to her as a protest. — Margie Cullen, USA Today, 8 June 2026 The Democrats’ evolution left many in their old factions, including Archie, to defect from the party. — Alex Rosado, The Orlando Sentinel, 25 June 2026 See All Example Sentences for defect

Word History

Etymology

Noun (1)

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

Verb

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

Noun (2)

Latin, from defectus (past participle of deficere to desert) + -or

First Known Use

Noun (1)

15th century, in the meaning defined at sense 1

Verb

1596, in the meaning defined at sense 1

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

Phrases Containing defect

Browse Nearby Words

defecator
defect
defectibility
See all Nearby Words

Cite this Entry

“Defect.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/defect. Accessed 7 Jul. 2026.

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Kids Definition

defect

1 of 2 noun
de·​fect ˈdē-ˌfekt How to pronounce defect (audio) di-ˈfekt How to pronounce defect (audio)
: a lack of something necessary for completeness or perfection

defect

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
defection
-ˈfek-shən
noun
defector
-ˈfek-tər How to pronounce defect (audio)
noun

Medical Definition

defect

noun
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

defect

noun
de·​fect ˈdē-ˌfekt, di-ˈfekt How to pronounce defect (audio)
: 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 How to pronounce defect (audio)
adjective
defectively adverb
defectiveness noun

More from Merriam-Webster on defect

Nglish: Translation of defect for Spanish Speakers

Britannica.com: Encyclopedia article about defect

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