argonaut vs opportunist

argonaut

noun
  • An adventurer on a dangerous but rewarding quest. 

  • Any of several species of shelled octopods of the family Argonautidae (of which only the genus Argonauta is not extinct). 

opportunist

noun
  • Someone who takes advantage of any opportunity to advance their own situation, placing expediency above principle. 

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