risk has 15 distinct synonyms spread across 6 of its 6 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 source of danger; a possibility of incurring loss or misfortune
“drinking alcohol is a health hazard”
the probability of becoming infected given that exposure to an infectious agent has occurred
the probability of being exposed to an infectious agent
expose to a chance of loss or damage
“We risked losing a lot of money in this venture”
take a risk in the hope of a favorable outcome
“When you buy these stocks you are gambling”
Synonyms, antonyms and the broader and narrower relations for risk come from Princeton University’s WordNet. Full sources and licences.