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 attack was unsuccessful, as Gwayne jumped to his nephew’s rescue in time, which only resulted in a couple of deaths and Ormund projectile vomiting at the smell.

— Jennifer Maas, Variety, 27 July 2026
Seattle Fire Department spokesperson Grace Nuñez said that its first responders attempted lifesaving efforts for two patients but were unsuccessful.

— Kayla Hayempour, NBC news, 26 July 2026

Definition of unsuccessful

Adjective

The group spent six futile months trying to prompt various artificial intelligence chatbots using Birman’s approach.

— Lyndie Chiou, Scientific American, 24 July 2026
Here, though, the entire enterprise is vile, and futile, and irredeemable, made worse by the self-delusion of the people who pursue it.

— Paul A. Thompson, Pitchfork, 21 July 2026

Definition of futile

Adjective

Donation delays can also make nonprofits appear inefficient, even when the payment infrastructure is beyond their control.

— Catherine LaCour, Forbes.com, 23 July 2026
The doctor argued that one strategy to more effectively organize the health system would be to implement new technology, noting that Venezuela still uses an inefficient paper-record system.

— Alfie Pannell, Miami Herald, 23 July 2026

Definition of inefficient

Adjective

However, this knowledge is ineffective without the wisdom healthcare delivery frequently requires; thus, these services cannot replace healthcare professionals, but can only augment their services and abilities.

— Forbes.com, Forbes.com, 26 July 2026
The latter concluded the practice is unscientific and ineffective, carrying risks of psychological harm, including suicidal ideation and depression.

— Kendrick Calfee, Kansas City Star, 24 July 2026

Definition of ineffective

Adjective

What this framework dismantles is a common and counterproductive myth—that friendships either spark instantly or are not worth pursuing.

— Wes Moss, Forbes.com, 10 July 2026
Johnson continued this week to push for his foolish and counterproductive desire to impose a $33-per-month tax on each Chicago job generated by the city’s largest private-sector employers.

— The Editorial Board, Chicago Tribune, 10 July 2026