deficiency

American  

[dih-fish-uhn-see] / dɪˈfɪʃ ən si /

Obsolete, deficience

noun

• deficiencies
  plural

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

Derived Forms

• nondeficiency
  noun
• predeficiency
  noun

Inflected Forms

Nouns

• deficiencies
  plural

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Etymology

Origin of deficiency

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

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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

See Examples For:

deficiency deficiencies

“Typically by around 10 to 12 years of age, people that are likely to have a deficiency in the enzyme have developed it to the capacity,” says Sibley.

From The Wall Street Journal ● Oct. 12, 2026

The founders wrote the Constitution in part to fix that deficiency.

From The Wall Street Journal ● Oct. 2, 2026

Existing clinical evidence on the link between B6 deficiency in Parkinson's patients and any potential impact it can have is still limited.

From BBC ● Oct. 1, 2026

“Conditions such as depression, lack of sleep, a low-functioning thyroid, and vitamin B12 deficiency can lead to memory loss that mimic the early stages of dementia,” Tan writes.

From Los Angeles Times ● Sep. 23, 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

My results showed various deficiencies, which the staff recommended treating with vitamin B and glutathione IV drips, acupuncture, cupping massages, osteopathy and daily hydro and mud therapy.

From The Wall Street Journal ● Oct. 2, 2026

"Nutrients such as vitamin D, iron and calcium are of particular concern during adolescence, when deficiencies may have lasting implications for skeletal health and overall development."

From Science Daily ● Sep. 24, 2026

So, arbitrarily boosting testosterone is not good for young men without deficiencies.

From Slate ● Sep. 13, 2026

Fifa claims Uefa's argument "suffers from a fundamental defect" and "legal deficiencies".

From BBC ● Sep. 3, 2026

His punishment is the Word, and his deficiencies are failures of words—as when he grows impatient with translation and strikes out precariously on his own, telling parables in his wildly half-baked Kikongo.

From "The Poisonwood Bible" by Barbara Kingsolver

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Related Words

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

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