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 sufficient to produce a desired effect; fully adequate. See Synonyms at effective.

adj. Producing the intended result; entirely adequate.

adj. Producing, or having adequate power or force to produce, an intended effect; adequate; efficient; operative; decisive.

Producing an effect, or the effect desired or intended; also, loosely, having adequate power or force to produce the effect: as, the means employed were effectual.

True; veracious.

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

adj. having legal efficacy or force

"Based on interviews and case studies with successful U.S. entrepreneurs and executives at large corporations, Sarasvathy found that master entrepreneurs rely on what she calls effectual reasoning."

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

ineffectual   

effectual adjudication   

efficacious    effectivity    effect    efficacity    efficacy    efficiency    efficient    effective   

efficacious    effective    adequate    efficient    operative    decisive   

speedy    immediate    efficacious    adequate    reasonable    salutary    decisive    forcible    justifiable    drastic