coin toss vs coin-toss

coin toss

noun
  • A particular instance where a coin is launched in the air, and whichever side that it lands on finalises a decision. 

  • An uncertain selection between two outcomes of similar likelihood, or between two objects of similar quality. 

coin-toss

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