possibility vs toss-up

possibility

noun
  • An option or choice, usually used in context with future events. 

  • The quality of being possible. 

  • A thing possible; that which may take place or come into being. 

toss-up

noun
  • A decision in which neither choice is clearly favorable or unfavorable, or for which the outcome does not matter. 

  • Either of two outcomes that are equally likely. 

  • The toss of a coin used to decide some issue. 

How often have the words possibility and toss-up occurred in a corpus of books? (source: Google Ngram Viewer )