deficient

1 of 2

adjective

de·​fi·​cient di-ˈfi-shənt 

1

: lacking in some necessary quality or element

deficient in judgment

bones deficient in calcium

2

: not up to a normal standard or complement (see complement entry 1 sense 1b(1)) : defective

deficient strength

… rusted and aging pipes … abetted by deficient maintenance and sabotage.

—Adam Nossiter

deficiently adverb

deficient

2 of 2

noun

: a person or thing that is deficient

Synonyms

Adjective

• fragmental
• fragmentary
• half
• halfway
• incomplete
• partial

Examples of deficient in a Sentence

Adjective

Several bridges in the city are structurally deficient.

a diet deficient in calcium can lead to weak bones

Recent Examples on the Web

Adjective

Finally, a doctor realized that Harvey, who had become a vegetarian a few years before, wasn’t getting enough protein and was deficient in a number of vitamins. —Les Carpenter, Washington Post, 31 July 2024

There’s a bit of research to suggest that being chronically deficient in magnesium can, in fact, raise your risk of poor sleep or a sleep disorder (like insomnia or excessive daytime sleepiness), perhaps by interfering with your circadian rhythm (a.k.a. —Erica Sloan, SELF, 26 Sep. 2024

Noun

People in certain age groups may also be more likely to become magnesium deficient, Gans said. —Maggie O'Neill, Verywell Health, 22 Oct. 2024

There is no other year in US history where the budget deficient was this large outside of a major war, like WW I & WW II, or dealing with a major recession, like 2008. —Beth Kindig, Forbes, 10 Oct. 2024

Word History

Etymology

Adjective

borrowed from Latin dēficient-, dēficiens, present participle of dēficere "to leave without enough, let down, be lacking, run short, fail," from dē- de- + facere "to make, bring about, perform, do" — more at fact

Noun

derivative of deficient entry 1

First Known Use

Adjective

1581, in the meaning defined at sense 1

Noun

1906, in the meaning defined above

Kids Definition

deficient

adjective

de·​fi·​cient

di-ˈfish-ənt

: lacking something necessary for completeness : not up to a given or normal standard

a diet deficient in proteins

deficient in their knowledge of history

deficiently adverb

Medical Definition

deficient

adjective

de·​fi·​cient di-ˈfish-ənt 

1

: lacking in some necessary quality or element

a deficient diet

When the body is deficient in vitamin C, these small blood vessels become fragile and break easily, causing small, bright red spots to appear around the hair follicles.

—Erica Julson, Healthline

2

: not up to a normal standard or capacity

deficient strength

Deficient sleep, which includes not getting enough sleep, irregularly timed sleep, poor quality sleep, and/or sleep disorders, impacts all aspects of functioning, including physical, emotional and occupational.

—Hailey Meaklim et al., Sleep Health

3

: having, relating to, or characterized by a genetic deletion or alteration

… cancer cells that are deficient for the tumor suppressor gene p53 can be outcompeted by cells in which p53 is still intact.

—Stephano Mello and Dirk Bohmann, eLife

… the deficient expression of a gene in the endometrium during the receptive phase … in infertile women.

—S. Henriquez et al., Molecular Human Reproduction

deficiently adverb

performed deficiently in clinical trials