efficacious

producing or capable of producing a desired result taking a cookie break while studying is one of the most efficacious ways of rejuvenating the mind that I have ever discovered Synonyms effectual, effective, efficient, fruitful, operative, potent, productiveRelated Words hyperefficient, ultraefficient; adequate, capable, competent; accomplished, adept, consummate, experienced, expert, masterly, practiced (also practised), proficient, skilled, skillful, versed, veteran, virtuoso; cogent, convincing, killer, sound, striking, telling, valid; active, dynamic; useful, working; applicable, feasible, functional, practicable, practical, realizable, usable (also useable), workableNear Antonyms counterproductive; incapable, incompetent, inexperienced, inexpert, unqualified, unseasoned, unskilled, unskillful; abortive, bootless, futile, vain; empty, hollow, idle, pointless, unavailing, unprofitable, unsuccessful; inoperative, worthlessAntonyms fruitless, ineffective, ineffectual, inefficient, inoperative, unfruitful, unproductive, useless