chance has 17 distinct synonyms spread across 7 of its 9 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a possibility due to a favorable combination of circumstances
“the holiday gave us the opportunity to visit Washington”
a risk involving danger
“you take a chance when you let her drive”
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”
Synonyms, antonyms and the broader and narrower relations for chance come from Princeton University’s WordNet. Full sources and licences.