revenant vs undead

revenant

noun
  • A supernatural being that returns from the dead; a zombie or ghost. 

  • A person or thing reborn. 

  • Someone who returns from a long absence. 

adj
  • Returning. 

undead

noun
  • A creature that is undead; that is, dead but still animate. 

  • Those creatures which are undead; that is, dead yet still animate. 

adj
  • Being animate, though non-living. 

  • Pertaining to a corpse, though having qualities of life. 

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