deficiency

American  

[dih-fish-uhn-see] / dɪˈfɪʃ ən si /

Obsolete, deficience

noun

plural

deficiencies

1. the state of being deficient; lack; incompleteness; insufficiency.

   Synonyms:

   scarcity, paucity, inadequacy, shortage

2. the amount lacked; a deficit.

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deficiency British  

/ dɪˈfɪʃənsɪ /

noun

1. the state or quality of being deficient

2. a lack or insufficiency; shortage

3. another word for deficit

4. biology the absence of a gene or a region of a chromosome normally present

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Other Word Forms

• nondeficiency noun
• predeficiency noun

Etymology

Origin of deficiency

First recorded in 1625–35; from Late Latin dēficientia, Latin dēficient- (stem of dēficiēns ); see origin at deficient, -ency

Explanation

A deficiency is an insufficient amount of something. If you feel sluggish and tired all day, you might have an iron deficiency, meaning you aren't eating enough iron-rich foods. You are most likely to hear the word deficiency in regard to health, like a sleep deficiency. But you can use deficiency to describe other kinds of lack — a deficiency of fun that occurred while your friends were out of town. Deficiency also means a failure or shortcoming, like a deficiency in math class, which might result in a notice from school — known as a deficiency — being mailed to your home.

Example Sentences

“GSK’s action does not affect the availability of generic leucovorin for patients with cerebral folate deficiency, or the labeling of leucovorin products,” an HHS spokesman said.

From The Wall Street Journal • Apr. 9, 2026

He attempts to disguise this deficiency with endless boasting about himself and endless denigration of others.

From Salon • Mar. 28, 2026

On Tuesday the FDA said it was in fact approving use of leucovorin for a rare condition called cerebral folate deficiency but not for autism.

From Barron's • Mar. 10, 2026

"Then, depending on a number of factors that may impact one's cancer risk, a fiber deficiency may increase your risk for certain cancers, such as colorectal, breast, and prostate cancer."

From Science Daily • Mar. 8, 2026

It wouldn’t have mattered anyway. 5-alpha-reductase deficiency syndrome is a skillful counterfeiter.

From "Middlesex: A Novel" by Jeffrey Eugenides

Related Words

• dearth
• defect
• failing
• failure
• fault
• flaw
• frailty
• glitch
• insufficiency
• lack
• scarcity
• shortage
• shortcoming
• weakness