Antonyms of noun effectiveness

1 of 2 senses of effectiveness

Sense 1
effectiveness, effectivity, effectualness, effectuality -- (power to be effective; the quality of being able to bring about an effect)
       Antonym of ineffectiveness (Sense 1)
      => ineffectiveness, ineffectualness, ineffectuality -- (lacking the power to be effective)

Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun effectiveness

2 senses of effectiveness

Sense 1
effectiveness, effectivity, effectualness, effectuality -- (power to be effective; the quality of being able to bring about an effect)
       => power, powerfulness -- (possession of controlling influence; "the deterrent power of nuclear weapons"; "the power of his love saved her"; "his powerfulness was concealed by a gentle facade")

Sense 2
potency, effectiveness, strength -- (capacity to produce strong physiological or chemical effects; "the toxin's potency"; "the strength of the drinks")
       => power, powerfulness -- (possession of controlling influence; "the deterrent power of nuclear weapons"; "the power of his love saved her"; "his powerfulness was concealed by a gentle facade")