Odds (noun)

1. The likelihood of something happening compared to something else.
2. The probability of an event occurring, usually expressed as a ratio of the number of possible outcomes that will work in favor of the event to the number of possible outcomes that will work against the event.
3. The difference in favor of one side or the other in a competition or contest.

Origin:

Middle english: from old english odde "a single number, a unit", of germanic origin; related to dutch odd and german odde, also to odd.

Examples:

1. The odds of winning the lottery are one in a million.
2. The odds of rain tomorrow are 50/50.
3. The odds are against him.
4. The odds are in her favor.
5. The odds of the horse winning are 2 to 1.