'Effectiveness' definitions:

Definition of 'effectiveness'

From: WordNet
noun
Power to be effective; the quality of being able to bring about an effect [syn: effectiveness, effectivity, effectualness, effectuality] [ant: ineffectiveness, ineffectuality, ineffectualness]
noun
Capacity to produce strong physiological or chemical effects; "the toxin's potency"; "the strength of the drinks" [syn: potency, effectiveness, strength]

Definition of 'Effectiveness'

From: GCIDE
  • Effectiveness \Ef*fect"ive*ness\, n. The quality of being effective. [1913 Webster]

Synonyms of 'effectiveness'

From: Moby Thesaurus