opine vs surmise

opine

verb
  • To have or express an opinion; to state as an opinion; to suppose, consider (that). 

  • To give one's formal opinion (on or upon something). 

noun
  • Any of a class of organic compounds, derived from amino acids, found in some plant tumours 

surmise

verb
  • To imagine or suspect; to conjecture; to posit with contestable premises. 

noun
  • Thought, imagination, or conjecture, which may be based upon feeble or scanty evidence; suspicion; guess. 

  • Reflection; thought; posit. 

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