( n. )
Power to produce effects; operation or energy of an agent or force; production of the effect intended; as, the efficacy of medicine in counteracting disease; the efficacy of prayer.
( n. )
Power to produce effects; operation or energy of an agent or force; production of the effect intended; as, the efficacy of medicine in counteracting disease; the efficacy of prayer.
Webster's Revised Unabridged English Dictionary. Пересмотренный полный словарь английского языка Webster. 2012