idoneous vs satisfactory

idoneous

adj

  • appropriate; suitable 

satisfactory

adj

  • Done to satisfaction; adequate or sufficient. 

  • Causing satisfaction; agreeable or pleasant; satisfying. 

  • Making atonement for a sin; expiatory. 

noun

  • The rating given to somebody or something that meets requirements without exceeding them. 

  • Somebody or something that meets requirements without exceeding them. 

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