defect

1 of 2

noun

de·​fect ˈdē-ˌfekt  di-ˈfekt 

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 2

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

Noun

• scar
• blotch
• fault
• deformity
• flaw
• distortion
• mark
• irregularity
• imperfection

Verb

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

Examples of defect in a Sentence

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.

Recent Examples on the Web

Noun

In the past, interior textures were used to cover up defects in the molding process. —Beth Livesay, AJC.com, 6 Mar. 2026

The 29-year-old took to Instagram on Tuesday to discuss undergoing surgery for a congenital heart defect. —Sharareh Drury, Entertainment Weekly, 4 Mar. 2026

Verb

Several Kurdish groups have released public statements hinting at imminent action and urging Iranian military forces to defect. —John Calabrese, The Conversation, 7 Mar. 2026

Several Iranian Kurdish groups have released public statements since the beginning of the war hinting at imminent action and urging Iranian military forces to defect. —Lauren Kent, CNN Money, 5 Mar. 2026

Word History

Etymology

Noun

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

First Known Use

Noun

15th century, in the meaning defined at sense 1

Verb

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