INEFFICACIOUS Synonyms: 72 Similar and Opposite Words

inefficacious

adjective

(ˌ)i-ˌne-fə-ˈkā-shəs

Definition of inefficacious

as in unsuccessful

not producing the desired result his efforts to restore the neglected houseplant back to health were belated and sadly inefficacious

Synonyms & Similar Words

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Antonyms & Near Antonyms

as in futile

producing no results an inefficacious medication for a rare form of tuberculosis

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 inefficacious Day — who grew up watching the spelling bee — came up with the concept of exploring the psyche of a winner with an ultimately inefficacious career in 2015 while at a UCB improv sketch-writing class. — NBC News, 6 Oct. 2020

Recent Examples of Synonyms for inefficacious

Adjective

Infantino has faced opposition since his unsuccessful attempt in July to bring private investors into a new FIFA commercial entity holding rights linked to competitions including the World Cup.

— CNN Money, CNN Money, 6 Nov. 2026
Cruz said that the dismissal of the rising cost of living led Republicans to be unsuccessful this election cycle.

— Hannah Demissie, ABC News, 5 Nov. 2026

Definition of unsuccessful

Adjective

The motives and rooting interest are uncomplicated and impossible to misinterpret, and each straightforward emotional beat is delivered with such sincere and amplified force that resistance is futile.

— Jim Hemphill, IndieWire, 6 Nov. 2026
Gina seems committed to another Heather takedown, no matter how futile those efforts are.

— Louis Peitzman, Vulture, 4 Nov. 2026

Definition of futile

Adjective

So, in some cases, high wattage can be an indicator of an inefficient appliance, not a more powerful one.

— BestReviews, Chicago Tribune, 3 Nov. 2026
The Churn of Creation Galaxies are remarkably inefficient at taking raw material — gas and dust — and turning it into stars.

— Perri Thaler, Quanta Magazine, 30 Oct. 2026

Definition of inefficient

Adjective

Raman has portrayed Bass as a weak and ineffective leader, pointing to her handling of the Palisades fire, the homelessness crisis and the city’s ongoing struggle to deliver basic services.

— Los Angeles Times, Los Angeles Times, 1 Nov. 2026
Hays served on the pre-platform committee at the 1952 Democratic National Convention and the platform committee in 1956, co-authoring weak and ineffective civil rights planks.

— Arkansas Online, Arkansas Online, 31 Oct. 2026

Definition of ineffective

Adjective

But their fervor ironically winds up being counterproductive, yielding a jumbled tonal mess that feels deadly serious one moment and like parody the next.

— Frank Scheck, HollywoodReporter, 15 Oct. 2026
The lesson is not to abandon the region but to rethink an approach that has become both too costly and counterproductive.

— Philip H. Gordon, Foreign Affairs, 12 Oct. 2026