surmise vs threaten

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. 

threaten

verb
  • To call into question the validity of (a belief, idea, or viewpoint); to challenge. 

  • To portend, or give a warning of. 

  • He threatened me with a knife. 

  • To make a threat against someone; to use threats. 

  • To menace, or be dangerous. 

  • To be close to equaling or surpassing (a record, etc.) 

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