Efficacy/ˈefɪkəsi/ Definition 1 of 3Pro Tip 1/3Result-Oriented Efficacy stresses on achieving specific, desired outcomes. The efficacy of the marketing campaign was seen in increased sales. Pro Tip 2/3Action's Impact Focus on the potency of an action's impact, not just the action itself. Their education initiative's efficacy was evident in higher literacy rates. Pro Tip 3/3Subtle Assurance Conveys a subtle assurance that something works well. His confidence in the efficacy of the new policy was contagious.