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

If a person is not deficient in iron, too much iron can cause significant problems.5 3. —Heather Jones, Verywell Health, 23 June 2025

Noted: Nearly 1 in 4 Americans is deficient in Vitamin D. —Hannah Yasharoff, USA Today, 17 June 2025

Noun

It is more commonly seen in countries where the soil is iodine deficient and there is no iodine added to salt. —Patty Weasler, Verywell Health, 27 May 2025

The use of vitamin A is linked to measles in that it is sometimes recommended for use in infected patients, especially children, who are already malnourished or nutrient deficient, according to the World Health Organization (WHO). —Eduardo Cuevas, USA TODAY, 7 Mar. 2025

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

Rhymes for deficient

• efficient
• omniscient
• proficient
• sufficient
• beneficent
• coefficient
• inefficient
• insufficient

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