concept vs opinion

concept

noun
  • Understanding retained in the mind, from experience, reasoning and imagination; a generalization (generic, basic form), or abstraction (mental impression), of a particular set of instances or occurrences (specific, though different, recorded manifestations of the concept). 

  • An abstract and general idea; an abstraction. 

  • A description of supported operations on a type, including their syntax and semantics. 

verb
  • to conceive; to dream up 

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 concept and opinion occurred in a corpus of books? (source: Google Ngram Viewer )