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

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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

The business hired attorneys to appeal the county’s assessment, Cerny said, but were unsuccessful.

— Evgenia Anastasakos, Chicago Tribune, 6 Sep. 2026
Alonso may have had an unsuccessful spell managing Real Madrid, but went unbeaten to win the Bundesliga with Bayer Leverkusen in his second season of senior management.

— Art de Roché, New York Times, 6 Sep. 2026

Definition of unsuccessful

Adjective

Requests for records from Princeton City Schools, Northwest Local Schools and Mason City Schools also largely proved futile.

— Grace Tucker, Cincinnati Enquirer, 30 Aug. 2026
In sick bay, M’Benga tries to remove the table and end his life so Chapel can give up on him, an effort that proves futile.

— Keith Phipps, Vulture, 27 Aug. 2026

Definition of futile

Adjective

As a business expands, growth has a way of exposing things like inefficient workflows and inconsistent processes that were once manageable, but on a smaller scale.

— Farzana Abdulhusein, Forbes.com, 4 Sep. 2026
Another common argument is that single-payer systems are inherently inefficient, as evidenced ostensibly by long waits for treatment suffered by patients in single-payer countries such as Canada.

— Business Columnist, Los Angeles Times, 3 Sep. 2026

Definition of inefficient

Adjective

David Shnaiderov, who directs the Nuclear Quantum division at Quantum X Labs, pointed out that simulating particle transport is useless without a practical way to represent real physical shapes.

— Aman Tripathi, Interesting Engineering, 4 Sep. 2026
However, this doesn’t mean the devices are completely useless.

— Andrew Paul, Popular Science, 2 Sep. 2026