effective vs operant

effective

adj
  • Having the power to produce a required effect or effects. 

  • approximate; Not describing the fundamental dynamic changes in some system as they happen. 

  • Efficient, serviceable, or operative, available for useful work. 

  • Having no negative coefficients. 

  • Producing a decided or decisive effect. 

  • Actually in effect. 

noun
  • a soldier fit for duty 

operant

adj
  • That operates to produce an effect. 

noun
  • Any of a class of behaviors that produce consequences by operating (i.e., acting) upon the environment. 

  • An operative person or thing. 

How often have the words effective and operant occurred in a corpus of books? (source: Google Ngram Viewer )