shifting vs wavering

shifting

noun
  • The phenomenon by which two or more constituents appearing on the same side of their common head exchange positions to obtain non-canonical order. 

  • A shift or change; a shifting movement. 

wavering

adj
  • Being in doubt; indecisive. 

  • Fluctuating, uncertain, undetermined, unsteady. 

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