beret vs watch cap

beret

noun
  • A type of round, brimless cap with a soft top and a headband to secure it to the head; usually culturally associated with France. 

watch cap

noun
  • A knitted cap, such as the one worn by a seaman when on watch. 

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