Chance
Possibility
Synonyms: Possibility, probability, likelihood, expectation, conceivability, plausibility, threat, hazard, fear, liability, opportunity, prospect, odds, likeliness, anticipation, feasibility, risk, menace, danger, peril, hope, and promise.
Opportunity
Synonyms: Opportunity, occasion, time, window (of opportunity), show, break, look-in, opening, turn, moment, slot, a kick at the can/cat, and shot.
Accident
Synonyms: Accident, serendipity, a twist of fate, fortuity, providence, hazard, (a bit of) luck, a fluke, happenstance, by accident, coincidentally, unintentionally, unwittingly, unawares, coincidence, fate, destiny, fortune, freak, a piece of good fortune, (a bit of) good luck, a happy chance, fortuitously, accidentally, serendipitously, inadvertently, unknowingly, and unconsciously.
Come across
Synonyms: Come across, run into, hit on, come upon, blunder on, meet (by chance), run against, run across, happen on, light on, stumble on, find by chance, and bump into.
Risk
Example Sentences
Take a chance on yourself.
They had a slim chance.
I missed my only chance.
He won by pure chance.