odds vs odds on

odds

noun
  • The ratio of the probability of an event happening to that of it not happening. 

  • I'd say the odds are strongly in favor of the sun rising tomorrow morning. 

  • An advantage given to a weaker opponent in order to equalize the game when playing casually, usually by removing one of the stronger player's pieces or by giving the weaker player more time. 

  • The ratio of winnings to stake in betting situations. 

odds on

adj
  • Likely: alternative spelling of odds-on 

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