deficient
Americanadjective
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lacking some element or characteristic; defective.
deficient in taste.
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insufficient; inadequate.
deficient knowledge.
noun
adjective
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lacking some essential; incomplete; defective
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inadequate in quantity or supply; insufficient
Other Word Forms
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” ( see also do 1)
Explanation
Deficient means not enough or not adequate. Maybe you were deficient in caffeine that day. Maybe you were lacking in study time. But no doubt about it: you came up with a deficient number of correct answers on the physics test. If your new car fund remains deficient, you don't have enough money to buy a new car. This presents a problem if your current car is deficient in some way — say, it no longer has enough engine power to drive up a hill. You may not feel you have what it takes to get a job, but the reality is you will have to choose between indulging your own deficiencies in this area or the car's.
Vocabulary lists containing deficient
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The vitamin D deficient group also required more opioid medication.
From Science Daily • May 20, 2026
I write here, understand, as a deficient moralist.
From The Wall Street Journal • Apr. 3, 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
Deere leverages AI to help farmers cut costs—by reducing labor required to operate equipment, minimizing wasted crop chemicals, and applying fertilizer more precisely where soil nutrients are deficient.
From Barron's • Feb. 2, 2026
Both Call and the Captain seemed to regard me as mentally deficient, since I couldn’t appreciate their marvelous humor.
From "Jacob Have I Loved" by Katherine Paterson
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
