extensional vs lucid

extensional

adj
  • Having great extent. 

  • Of or pertaining to extension. 

lucid

adj
  • clear; easily understood 

  • bright, luminous, translucent or transparent 

  • mentally rational; sane 

noun
  • A lucid dream. 

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