elderly vs period piece

elderly

noun
  • Older people as a whole. 

  • An elderly person. 

adj
  • old; having lived for relatively many years. 

  • Of an object, being old-fashioned or frail due to aging. 

period piece

noun
  • A work of art or drama which evokes a particular historical era. 

  • A work which evokes the era in which it was produced, but may not have any other especial features. 

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