deficient

[dih-fish-uhnt] / dɪˈfɪʃ ənt /

ADJECTIVE

imperfect, inadequate

Synonyms

STRONGEST

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

WEAK

amiss bad damaged exiguous found wanting infrequent injured marred meager not cut out for not enough not make it not up to scratch outta gas rare scant scanty second fiddle second string short shy sketchy third-string unassembled unequal unfinished wanting

Antonyms

STRONGEST

abundant adequate enough perfect strong sufficient

WEAK

ample excessive faultless flawless satisfactory superfluous

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.

“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

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

Lacking one of their top players with guard Skyy Clark sidelined by a hamstring injury, the Bruins also were deficient in many other areas.

From Los Angeles Times • Jan. 6, 2026

Cal Tech was not the place—Linus was too great a man to waste his time teaching a mathematically deficient biologist.

From "Double Helix" by James D. Watson

Vocabulary lists containing deficient

Tuesdays with Morrie

Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!

Oh, No! Synonyms for "Bad"

Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!

50 Words from Jane Austen's "Pride & Prejudice"

Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!