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
Derived 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.
FCC Chairman Brendan Carr said in a statement Thursday that Disney filed its applications to renew its broadcast licenses only after the company was told its previous answers were “disingenuous, deficient and improper.”
From Los Angeles Times • May 28, 2026
Vomiting was only reported in the deficient group, although researchers said the difference was too small to be considered statistically significant.
From Science Daily • May 20, 2026
The Texas Department of State Health Services found Camp Mystic’s emergency plans deficient; the camp plans to use a neighboring site.
From The Wall Street Journal • Apr. 24, 2026
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
I stumbled to my feet; my leg dragged, deficient in its circulation.
From "The Astonishing Life of Octavian Nothing, Traitor to the Nation, Volume I: The Pox Party" by M.T. Anderson
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.
