deficient

American  

[dih-fish-uhnt] / dɪˈfɪʃ ənt /

adjective

1. lacking some element or characteristic; defective.

   deficient in taste.

2. insufficient; inadequate.

   deficient knowledge.

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noun

1. a person who is deficient, especially one who is mentally defective.

deficient British  

/ dɪˈfɪʃənt /

adjective

1. lacking some essential; incomplete; defective

2. inadequate in quantity or supply; insufficient

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Other Word Forms

• deficiently adverb
• nondeficient adjective
• nondeficiently adverb
• predeficient adjective
• predeficiently adverb
• undeficient adjective
• undeficiently adverb

Etymology

Origin of deficient

First recorded in 1575–85; from Latin dēficient-, stem of dēficiēns “failing,” present participle of dēficere “to fail, run short, lack, weaken,” from dē- de- + ficere, combining form of facere “to do, make” ( do ¹ )

Example Sentences

Iran, which is an IMO member but does not sit on its council, hit out at the declaration, branding it "one-sided, unfair, inaccurate and legally deficient".

From Barron's • Mar. 19, 2026

The county conducted an audit of Harm Reduction-SD in April 2023 that revealed “significant financial control weaknesses including insufficient bank reconciliations and a deficient general ledger,” prosecutors allege.

From Los Angeles Times • Feb. 19, 2026

“Our animals and us are actually super deficient in light, especially the most healing wavelengths that we have,” says Jackie Jolie, CEO of AnimaSol.

From The Wall Street Journal • Jan. 28, 2026

After MI5 apologised, we then showed that inquiries into what happened by MI5 and the government were deficient and unreliable, with further falsehoods provided to the court.

From BBC • Jan. 25, 2026

It hadn’t occurred to me how thoughtlessly deficient nature is in this regard.

From "A Walk in the Woods" by Bill Bryson

Related Words

• defective
• faulty
• flawed
• impaired
• incomplete
• inferior
• insufficient
• lacking
• scarce
• skimpy
• unsatisfactory
• weak