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
-
lacking some essential; incomplete; defective
-
inadequate in quantity or supply; insufficient
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 )
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.
These provide calories but lack the sterols bees need, leaving colonies nutritionally deficient.
From Science Daily • Mar. 27, 2026
The agreement Barnett reached with LaBeouf “contained a deficient and unlawful NDA that is unenforceable,” under California’s Stand Together Against Non-Disclosure Act, according to the complaint.
From Los Angeles Times • Mar. 26, 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
"If it turns out the shipowners were deficient, they will expect the full force of the law," Lopez told reporters.
From Barron's • Jan. 27, 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.
