probability

(noun) a measure of how likely it is that some event will occur; a number expressing the ratio of favorable cases to the whole number of cases possible. Synonyms: chance. Example: "The probability that an unbiased coin will fall with the head up is 0.5."

(noun) the quality of being probable; a probable event or the most probable event. Examples: "For a while mutiny seemed a probability." "Going by past experience there was a high probability that the visitors were lost."