inconsistent vs vacillating

inconsistent

adj
  • Having the property that a contradiction can be derived. 

  • Lacking internal consistency; self-contradicting; not compatible with itself. 

  • Not consistent or coherent in thought or behavior. 

  • Not compatible (with another thing); incompatible, discrepant, at odds. 

vacillating

adj
  • Liable to vacillate. 

noun
  • Vacillation. 

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