betray vs unfold

betray

verb
  • To disclose or indicate, for example something which prudence would conceal; to reveal unintentionally. 

  • To violate the confidence of, by disclosing a secret, or that which one is bound in honor not to make known. 

  • To prove faithless or treacherous to, as to a trust or one who trusts; to be false to; to deceive. 

  • To deliver into the hands of an enemy by treachery or fraud, in violation of trust; to give up treacherously or faithlessly. 

  • To mislead; to expose to inconvenience not foreseen; to lead into error or sin. 

  • To lead astray; to seduce (as under promise of marriage) and then abandon. 

unfold

verb
  • To reveal. 

  • To undo a folding. 

  • To release from a fold or pen. 

  • To turn out; to happen; to develop. 

  • To open (anything covered or closed); to lay open to view or contemplation; to bring out in all the details, or by successive development. 

noun
  • In functional programming, a kind of higher-order function that is the opposite of a fold. 

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