crass vs unproper

crass

adj
  • coarse; crude; unrefined or insensitive; lacking discrimination 

  • materialistic 

  • dense 

  • Lacking finesse; crude and obvious. 

unproper

adj
  • Improper, not according with good standards of behaviour; indecent, indecorous. 

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