Noun

• S: (n) effectiveness, effectivity, effectualness, effectuality (power to be effective; the quality of being able to bring about an effect)
• direct hyponym / full hyponym
• S: (n) incisiveness, trenchancy (keenness and forcefulness of thought or expression or intellect)
• S: (n) efficacy, efficaciousness (capacity or power to produce a desired effect) "concern about the safety and efficacy of the vaccine"
• attribute
• direct hypernym / inherited hypernym / sister term
• antonym
• derivationally related form