antediluvial vs prediluvian

antediluvial

adj

  • Of or pertaining to a time before Noah's flood. 

  • Antiquated. 

prediluvian

adj

  • Before the Flood; antediluvian. 

noun

  • One who lived before the Flood; an antediluvian. 

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