seignior vs viscount

seignior

noun
  • A feudal lord; a nobleman who held his lands by feudal grant; any lord (holder) of a manor 

  • A title of respect, formerly corresponding (especially in France) approximately to Sir. 

viscount

noun
  • A member of the peerage, above a baron but below a count or earl. 

  • Any of various nymphalid butterflies of the genus Tanaecia. Other butterflies in this genus are called earls and counts. 

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