coin flip vs toss-up

coin flip

noun
  • Synonym of coin toss 

toss-up

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

  • 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. 

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