erratic vs wavering

erratic

adj
  • Unsteady, random; prone to unexpected changes; not consistent. 

  • Deviating from normal opinions or actions; eccentric; odd. 

noun
  • A rock moved from one location to another, usually by a glacier. 

  • Anything that has erratic characteristics. 

wavering

adj
  • Fluctuating, uncertain, undetermined, unsteady. 

  • Being in doubt; indecisive. 

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