insubstantial vs privative

insubstantial

adj

  • Lacking substance; not real or strong. 

privative

adj

  • consisting in the absence of something; negative 

  • causing privation; depriving 

  • indicating the absence of something 

noun

  • something that causes privation or indicates an absence 

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