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.