in·​ef·​fi·​ca·​cious (ˌ)i-ˌne-fə-ˈkā-shəs How to pronounce inefficacious (audio)
: lacking the power to produce a desired effect : ineffective
inefficaciously adverb
inefficaciousness noun

Examples of inefficacious in a Sentence

his efforts to restore the neglected houseplant back to health were belated and sadly inefficacious an inefficacious medication for a rare form of tuberculosis
Recent Examples on the Web Most wore inefficacious cloth masks, too. James Lileks, National Review, 25 Aug. 2022 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

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'inefficacious.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1658, in the meaning defined above

Time Traveler
The first known use of inefficacious was in 1658

Dictionary Entries Near inefficacious

Cite this Entry

“Inefficacious.” Dictionary, Merriam-Webster, Accessed 25 Feb. 2024.

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