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
the probability that an unbiased coin will fall with the head up is 0.5|if that phone call is for me, chances are it's my wife
Synonym: chance
noun.
the quality of being probable; a probable event or the most probable event
for a while mutiny seemed a probability|going by past experience there was a high probability that the visitors were lost
Antonym: improbability