Definition

Not able to achieve the intended result or effect; ineffective.

Example

The new policy was deemed inefficacious in reducing pollution levels.

Conversation

I tried that new study method, but it felt really inefficacious for me.

Really? I thought it worked well for others.

Yeah, I guess everyone learns differently, but it just didn't click.

That's fair; sometimes you have to find what works best for you.

Synonyms & Antonyms

Root Explanation

Inefficacious → It is formed from "in-" (meaning not) and "efficax" (from Latin, meaning effective or producing the desired effect) and the suffix "-ious" (meaning full of or having the quality of). The word "inefficacious" means not producing the desired effect or result.

Memory Tip

Think of 'not' ('in-') being combined with 'effective' ('efficax') to remember that 'inefficacious' means something that does not produce the desired effect.

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