morning vs nychthemeron

morning

noun
  • The early part of the day, especially from dawn to noon. 

  • The first alcoholic drink of the day; a morning draught. 

  • The early part of anything. 

intj
  • A greeting said in the morning; shortening of good morning 

nychthemeron

noun
  • A period of one day and one night, a date: in the West, this is a period of 24 consecutive hours. 

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