What does defect mean?
A defect is a fault or imperfection — anything that falls short of how a thing ought to be. It applies most naturally to manufactured goods and structures: a car with a defect in its brakes, a building with defects in its foundations. It also extends to people, describing physical impairments such as a hearing defect, or flaws of character and judgement, though this latter use can sound harsh or clinical. As a verb, defect has a strikingly different meaning: to abandon one's country or cause and go over to an opposing side, as when athletes and scientists defected across the Iron Curtain during the Cold War. The word comes from Latin deficere, meaning 'to fail or be wanting', which is also the source of 'deficiency' and 'deficit'. Whether describing a faulty product or a change of loyalty, defect always connotes failure to meet an expected standard.
A fault, flaw, or imperfection in a thing, product, or system that impairs its quality, value, or function.
"Every unit sold was recalled because of a potentially dangerous electrical defect."
In law and consumer protection, a 'defect' often carries a precise technical meaning — a condition rendering a product unreasonably unsafe or unfit for purpose.
A weakness or shortcoming in a person's body, mind, or character.
"She has a slight hearing defect in her left ear."
To desert one's country, party, or cause in order to join an opposing one.
"Several leading scientists defected during the height of the Cold War."
Regular plural; frequently used in plural when discussing manufacturing faults, congenital conditions, or lists of shortcomings.
"The inspection revealed several defects in the welds along the pipeline."
Say it as DEE-fect and you're describing a crack in the wing; say di-FECT and you're a Cold War spy boarding a plane to the other side.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of defect
Defect derives from the Latin verb deficere, formed from de- ('down, away') plus facere ('to do, make'), literally meaning 'to fail, be wanting, or fall short'. English adopted it in the late 16th century both as a noun denoting a lack or failing and later as a verb meaning to forsake one's allegiance. It shares this root with related borrowings such as 'deficiency', 'deficit', and, through the same Latin facere, words like 'effect' and 'efficient', all carrying the underlying sense of doing, making, or falling short.
Related word forms
How defect is actually used
Note the stress shift between parts of speech: the noun carries stress on the first syllable (DEE-fect), while the verb stresses the second (di-FECT). The noun is common in technical, medical, legal and quality-control contexts and often implies something that should have been made correctly but wasn't; 'defect' can sound more clinical than 'fault' or 'flaw'. The verb is strongly associated with politics, espionage and ideological allegiance, especially during the Cold War.
Easily confused with defect
A deficit is a shortage or shortfall, especially of money or resources, while a defect is a fault or imperfection in a thing itself.
To deflect is to turn something aside from its course, whereas a defect is the fault or flaw that exists within something.