revocable vs shifting

revocable

adj
  • Having the ability of being revoked; capable of being revoked. 

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. 

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