melancholy vs sad

melancholy

adj
  • Affected with great sadness or depression. 

noun
  • Great sadness or depression, especially of a thoughtful or introspective nature. 

  • Black bile, formerly thought to be one of the four "cardinal humours" of animal bodies. 

sad

adj
  • Causing sorrow; lamentable. 

  • Soggy (to refer to pastries). 

  • Of colours: dark, deep; later, sombre, dull. 

  • Appearing sorrowful. 

  • Feeling sorrow; sorrowful, mournful. 

  • Poor in quality, bad; shameful, deplorable; later, regrettable, poor. 

  • Unfashionable; socially inadequate or undesirable. 

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