deficiency

noun

de·​fi·​cien·​cy di-ˈfi-shən-sē 

plural deficiencies

1

: the quality or state of being defective or of lacking some necessary quality or element : the quality or state of being deficient : inadequacy

suffers from a deficiency of critical thinking

2

: an amount that is lacking or inadequate : shortage

staffing deficiencies

: such as

a

: a shortage of substances necessary to health

a vitamin C deficiency

hormone deficiencies

b

genetics : deletion sense 2b(1)

Synonyms of deficiency

• shortage
• lack

Examples of deficiency in a Sentence

The disease may be caused by nutritional deficiencies.

The book's major deficiency is its poor plot.

a deficiency of vitamin C

There are several deficiencies in his plan.

The accident was caused by deficiencies in the engine.

Recent Examples on the Web

Others, primarily older, Black residents from the West and South sides, raised alarms about day-to-day policing issues in the parts of the city most afflicted by crime and other quality-of-life deficiencies. — Sam Charles, Chicago Tribune, 13 Nov. 2026

Posters are claiming that iron deficiency can be seen on your face via symptoms such as dark under-eyes, pale and dry skin, and hair loss. — Will Barker, TheWeek, 12 Nov. 2026

Ten games into the season, those contradictions have produced a 2-8 record, several encouraging developments and some statistical deficiencies that demand attention ahead of Wednesday’s visit to the New Orleans Pelicans. — C.j. Holmes, New York Daily News, 11 Nov. 2026

The research published last week highlights the consequences of declining uptake, including vitamin K deficiency bleeding. — Emma Marsden, MSNBC Newsweek, 11 Nov. 2026

Word History

Etymology

defici(ent) entry 1 + -ency

First Known Use

1603, in the meaning defined at sense 1

Phrases Containing deficiency

• acquired immune deficiency syndrome
• deficiency disease
• mental deficiency

Rhymes for deficiency

• efficiency
• proficiency
• sufficiency
• immunodeficiency
• inefficiency
• insufficiency

Kids Definition

deficiency

noun

de·​fi·​cien·​cy di-ˈfish-ən-sē 

plural deficiencies

1

: the quality or state of being deficient

2

: the quality or state of being inadequate

especially : a shortage of substances necessary to health

Medical Definition

deficiency

noun

de·​fi·​cien·​cy di-ˈfish-ən-sē 

plural deficiencies

1

: a shortage of substances (as vitamins) necessary to health

2

: deletion

Legal Definition

deficiency

noun

de·​fi·​cien·​cy di-ˈfi-shən-sē 

plural deficiencies

: an amount that is lacking or inadequate: as

a

: the difference between the amount of tax owed and the amount of tax paid

b

: the difference between the amount owed under a security agreement and the amount the creditor is able to recover upon default of the debtor by selling the collateral