longbeard vs older adult

longbeard

noun
  • Synonym of greybeard (“an old man”) 

  • A man with a long beard. 

  • Synonym of greybeard (“experienced long-time member of a group”) 

  • Synonym of greybeard (“a bellarmine”) 

older adult

noun
  • An old person. 

  • Used other than figuratively or idiomatically: see older, adult. 

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