in use vs obsolete

in use

prep
  • Currently being used. 

obsolete

verb
  • To cause to become obsolete. 

adj
  • No longer in use; gone into disuse; disused or neglected (often in favour of something newer). 

  • Imperfectly developed; not very distinct. 

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