This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

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adj. Producing or capable of producing a desired effect. See Synonyms at effective.

adj. effective

adj. Possessing the quality of being effective; productive of, or powerful to produce, the effect intended.

Producing the desired effect; having power adequate to the purpose intended; effectual in operation or result.

Synonyms Efficient, Effectual, etc. (see effective); active, operative, energetic.

adj. marked by qualities giving the power to produce an intended effect

adj. producing or capable of producing an intended result or having a striking effect

"The special grace which we refer to as efficacious is sometimes called irresistible grace."

effective    impelling    rough-and-ready    trenchant    hard-hitting    impressive    telling   

effectual    effectivity    effect    efficacity    efficacy    efficiency    efficient    effective   

effectual    effective   

Ignatius    audacious    capacious    ceraceous    crustaceous    fallacious    flirtatious    gracious    hellacious    herbaceous   

effectual    beneficial    proficient    feasible    palatable    satisfactory    apt    serviceable    amenable    helpful