inefficacious

[ in-ef-i-key-shuhs ]

adjective

1. not able to produce the desired effect; ineffective.

inefficacious

/ ˌɪnɛfɪˈkæsɪtɪ; ˌɪnɛfɪˈkeɪʃəs; ɪnˈɛfɪkəsɪ /

adjective

1. failing to produce the desired effect

Derived Forms

• ˌineffiˈcaciously, adverb
• inefficacy, noun

Other Words From

• inef·fi·cacious·ly adverb
• inef·fi·cacious·ness in·ef·fi·cac·i·ty [in-ef-i-, kas, -i-tee], noun

Word History and Origins

Origin of inefficacious¹

First recorded in 1650–60; in- ³ + efficacious

Example Sentences

I signed because I wanted to see if a new approach might save me from the miseries of standard treatments that had proven inefficacious.

From New York Times

Meanwhile, the public has received only dribs and drabs of the investigation’s contents — all of which affirm the appropriately established understanding that the CIA’s post-9/11 use of torture was rampant and inefficacious.

From Salon

The report is an important recognition that this preemptive, prefigurative mode of policing and surveillance is not only unconstitutional, but also practically inefficacious if the aim is preventing terror attacks.

From Salon

The report is an important recognition that preemptive, prefigurative mode of policing and surveillance is not only unconstitutional, but also practically inefficacious if the aim is preventing terror attacks.

From Salon

Every argument was brought forward to induce him to stay in La Rochelle, but every argument proved inefficacious.

From Project Gutenberg