DEFICIENT Synonyms: 257 Similar and Opposite Words

deficient

adjective

di-ˈfi-shənt

Definition of deficient

as in incomplete

lacking some necessary part a diet deficient in calcium can lead to weak bones

Synonyms & Similar Words

Relevance

Antonyms & Near Antonyms

as in unacceptable

falling short of a standard woefully deficient eyesight kept him out of military service

Synonyms & Similar Words

Antonyms & Near Antonyms

as in lacking

not coming up to an expected measure or meeting a particular need too deficient in common sense to be trusted to stay by himself

Synonyms & Similar Words

Antonyms & Near Antonyms

Example Sentences

Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.

Recent Examples of deficient Yet researchers have found that nearly a third of adults in the United States are iron deficient. — Anahad O’Connor, Washington Post, 27 Aug. 2026 Many people today have inherited and perpetuated this way of thinking without knowing it, including those who are deemed deficient by it. — Hilary Smith, The Conversation, 25 Aug. 2026 The Dolphins might be talent-deficient for two years, especially at wide receiver and possibly tight end. — Chris Perkins, Sun Sentinel, 17 Aug. 2026 Many people are deficient in vitamin D due to limited sunlight exposure and few natural food sources. — Kirsten Nunez, Martha Stewart, 12 Aug. 2026 See All Example Sentences for deficient

Recent Examples of Synonyms for deficient

Adjective

An underfunded, conditional, or incomplete proposal may not qualify, but that determination depends on the offer’s exact wording and the governing law.

— Ethan Stone, Miami Herald, 23 Sep. 2026
At the same time, if your vendor records are incomplete, those inconsistencies will carry over, regardless of how sophisticated your AI tool is.

— John Gronen, Forbes.com, 23 Sep. 2026

Definition of incomplete

Adjective

Laying an egg against the Raiders in Year 3 of the Harbaugh era is unacceptable.

— Alejandro Avila OutKick, FOXNews.com, 21 Sep. 2026
Kip Dellinger Santa Monica The type of play by the Chargers on Sunday was completely unacceptable, lackluster and disappointing for a team with Super Bowl aspirations.

— Los Angeles Times, Los Angeles Times, 19 Sep. 2026

Definition of unacceptable

Adjective

With access from both the east and west sides of the campus, the museum’s park creates a pedestrian connection between Vermont Avenue to the west and the rest of Exposition Park to the east, which was previously lacking.

— Christina Merino, Daily News, 2 Sep. 2026
Ohio's fittest cities don't rank in the national top 25, but that doesn't mean the Buckeye State is unhealthy or lacking amenities.

— Alex Perry, Cincinnati Enquirer, 28 Aug. 2026

Definition of lacking

Adjective

Who wouldn’t like to whip out a formula that enabled you to judge this action as evil and the other as merely wrong?

— Literary Hub, Literary Hub, 18 Sep. 2026
The helicopter, which was used by NBC and Telemundo, crashed about two hours after police say Rios drove her 2004 Ford Expedition the wrong way down a busy avenue, ran a red light and struck a vehicle before hitting the bus.

— Arkansas Online, Arkansas Online, 17 Sep. 2026

Definition of wrong

Adjective

Some micromanaging comes from inadequate training or making assumptions, Adeshola adds.

— Sarah Jackson, CNBC, 21 Sep. 2026
That comes after the school district did not officially apply for the leftover money, which a CPS spokesperson told the Tribune was an inadequate amount to meaningfully help with its yawning shortfall.

— A.D. Quig, Chicago Tribune, 20 Sep. 2026

Definition of inadequate

Adjective

Renovation will only yield temporary improvement unless the original cause of a poor-quality lawn is remedied.

— Mary Marlowe Leverette, Southern Living, 19 Sep. 2026
The consequences of a poor performance in the takeaway department sets a very high standard for rookies, something that can only bode well for the future.

— Miami Herald, Miami Herald, 19 Sep. 2026

Definition of poor

Adjective

Two days later, the Los Angeles County Sheriff’s Department released him from custody, citing insufficient evidence to charge him.

— Connor Sheets, Los Angeles Times, 16 Sep. 2026
The grand jury found insufficient evidence to charge anyone criminally, and the two have denied any wrongdoing.

— Zoe Millán, Miami Herald, 16 Sep. 2026

Definition of insufficient

Adjective

As Trump slides toward lame-duck status, cleavages within the group and between it and traditional progressives are becoming more salient.

— David A. Graham, The Atlantic, 18 Sep. 2026
The next big issue for me was that Axl shimmied from side to side with an unusual snakelike move that struck me as effeminate and lame.

— Jon Blistein, Rolling Stone, 15 Sep. 2026

Definition of lame

Browse Nearby Words

deficiency

deficient

deficiently

See all Nearby Words

Cite this Entry

Style

“Deficient.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/deficient. Accessed 25 Sep. 2026.

Copy Citation

Synonyms of deficient

adjective

Example Sentences

Browse Nearby Words

Cite this Entry

More from Merriam-Webster

Word of the Day

tactile

Popular in Grammar & Usage

Do You Need a New Language Peeve?

More Commonly Mispronounced Words

Why do we use apostrophes to show possession?

Merriam-Webster’s Great Big List of Words You Love to Hate

'A' or 'an'? What about before 'h'? An Indefinite Article Guide

Popular in Wordplay

The Longest Long Words List

9 Words That Sound Like Insults But Aren't

Back to School Vocabulary

14 Phobias You Probably Haven't Heard Of

The Words of the Week - Sept. 25

Popular

Do You Need a New Language Peeve?

The Longest Long Words List

9 Words That Sound Like Insults But Aren't

Games & Quizzes