idea vs opinion

idea

noun
  • More generally, any result of mental activity; a thought, a notion; a way of thinking. 

  • An abstract archetype of a given thing, compared to which real-life examples are seen as imperfect approximations; pure essence, as opposed to actual examples. 

  • A conception in the mind of something to be done; a plan for doing something, an intention. 

  • A purposeful aim or goal; intent 

  • A musical theme or melodic subject. 

  • An image of an object that is formed in the mind or recalled by the memory. 

  • A vague or fanciful notion; a feeling or hunch; an impression. 

opinion

noun
  • The judgment or sentiment which the mind forms of persons or things; estimation. 

  • A belief, judgment or perspective that a person has formed, either through objective or subjective reasoning, about a topic, issue, person or thing. 

  • a judicial opinion delivered by an Advocate General to the European Court of Justice where he or she proposes a legal solution to the cases for which the court is responsible 

  • The formal decision, or expression of views, of a judge, an umpire, a doctor, or other party officially called upon to consider and decide upon a matter or point submitted. 

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