ambivalent vs undecided

ambivalent

adj
  • Alternately having one opinion or feeling, and then the opposite. 

  • Simultaneously experiencing or expressing opposing or contradictory feelings, beliefs, or motivations. 

undecided

adj
  • Uncommitted, not having reached a decision. 

  • Open and not yet settled or determined. 

noun
  • A voter etc. who has not yet come to a decision. 

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