burgee vs vexillum

burgee

noun
  • A flag, usually a broad tapering pennant, often with a swallowtail, flown by yachts to identify the owner's yacht club. 

vexillum

noun
  • A flag, banner, or standard. 

  • A company of troops serving under one standard. 

  • The upper petal of a papilionaceous flower. 

  • The sign of the cross. 

  • The rhachis and web of a feather taken together. 

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