ballot vs secret ballot

ballot

noun
  • The process of voting, especially in secret; a round of voting. 

  • The total of all the votes cast in an election. 

  • A list of candidates running for office; a ticket. 

  • Originally, a small ball placed in a container to cast a vote; now, by extension, a piece of paper or card used for this purpose, or some other means used to signify a vote. 

verb
  • To draw lots. 

  • To vote or decide by ballot. 

secret ballot

noun
  • The voting system involving ballots available only at official polling places, prepared at public expense, containing the names of all candidates, and marked in secret at the polling places. 

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