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

“Inadequate nutrition, particularly vitamin A deficiency, can impair the lining of the digestive tract, predisposing birds to inflammation and secondary illness.”

From Los Angeles Times • Apr. 20, 2026

“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

The findings point to the need for additional research to better understand how color vision deficiency affects disease detection.

From Science Daily • Mar. 10, 2026

He and many other scientists believed that cancer was caused by either a virus or an immune system deficiency, so Southam decided to use HeLa to test those theories.

From "The Immortal Life of Henrietta Lacks" by Rebecca Skloot

Related Words

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