alcove vs exedra

alcove

noun
  • A small recessed area set off from a larger room. 

  • A shady retreat. 

exedra

noun
  • A semicircular recess, with stone benches, used as a place for discussion. 

  • A curved bench with a high back. 

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