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not effective

ADJECTIVE

ineffective

Synonyms

STRONGEST

feeble fruitless futile impotent inadequate incompetent indecisive ineffectual inefficient inept limited null powerless unable unproductive unprofitable unsuccessful worthless

WEAK

abortive anticlimactic barren bootless defeasible emasculate epicene feckless forceless idle inefficacious inferior innocuous inoperative lame neutralized no-go nugatory paltry slack-spined spineless unavailable unavailing unfruitful vain void withered

Antonyms

STRONGEST

able adequate capable competent dexterous effective effectual efficient expert fit fruitful potent powerful productive profitable skillful strong successful sufficient useful valuable worthwhile worthy

Example Sentences

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not effective

The report's authors said their findings were consistent with two other studies and, when taken together, provided "strong evidence that the MenB vaccine is not effective for gonorrhea prevention".

From BBC ● Jul. 8, 2026

The jab is not effective at preventing the transmission of bacteria between people.

From BBC ● Jun. 12, 2026

That’s not effective fraud protection — that’s a broken system that is wasting money and creating friction with customers and vendors.

From MarketWatch ● Apr. 22, 2026

It also opens the possibility that treating hypercortisolism could provide a new way to lower blood pressure when standard therapies are not effective.

From Science Daily ● Mar. 30, 2026

“Or it’s not effective on egglets,” Jordie puts in.

From "Linked" by Gordon Korman

not effective

Example Sentences

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