counterfactual vs iffy

counterfactual

adj
  • Contrary to known or agreed facts; untrue. 

  • Of or in comparison to a hypothetical state of the world. 

noun
  • A conditional statement in which the conditional clause is false. 

  • A claim, hypothesis, or other belief that is contrary to the facts. 

  • A hypothetical state of the world, used to assess the impact of an action. 

iffy

adj
  • Of dubious authenticity, legitimacy or legality. 

  • Uncertain or chancy. 

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