Chance

the absence of any cause of events that can be predicted, understood, or controlled: often personified or treated as a positive agency:
Chance governs all.
luck or fortune:
a game of chance.
a possibility or probability of anything happening:
a fifty-percent chance of success.
an opportune or favorable time; opportunity:
Now is your chance.
Baseball. an opportunity to field the ball and make a put-out or assist.
a risk or hazard:
Take a chance.
a share or ticket in a lottery or prize drawing:
The charity is selling chances for a dollar each.
chances, probability:
The chances are that the train hasn’t left yet.
Midland and Southern U.S. a quantity or number (usually followed by of).
Archaic. an unfortunate event; mishap.
to happen or occur by chance:
It chanced that our arrivals coincided.
to take the chances or risks of; risk (often followed by impersonal it):
I’ll have to chance it, whatever the outcome.
not planned or expected; accidental:
a chance occurrence.
chance on/upon, to come upon by chance; meet unexpectedly:
She chanced on a rare kind of mushroom during her walk through the woods.
by chance, without plan or intent; accidentally:
I met her again by chance in a department store in Paris.
on the chance, in the mild hope or against the possibility:
I’ll wait on the chance that she’ll come.
on the off chance, in the very slight hope or against the very slight possibility.
Contemporary Examples

Juan Pablo Has Ruined ‘The Bachelor’ Brandy Zadrozny February 10, 2014
British Man Has BRCA2 Gene, Removes Prostate Tom Sykes May 19, 2013
Could Ariel Castro Be Linked to the 1981 Murder of Tammy Seals? Christine Pelisek May 10, 2013
The Orwell Prize Has a Chance to Redeem Itself David Frum March 28, 2012
The GOP Flees to the Cleve James Poulos July 8, 2014

Historical Examples

Buffalo Bill’s Spy Trailer Colonel Prentiss Ingraham
The Spenders Harry Leon Wilson
Youth Joseph Conrad
The Spenders Harry Leon Wilson
Frenzied Finance Thomas W. Lawson

noun

the unknown and unpredictable element that causes an event to result in a certain way rather than another, spoken of as a real force
(as modifier): a chance meeting, related adjective fortuitous

fortune; luck; fate
an opportunity or occasion
a risk; gamble: you take a chance with his driving
the extent to which an event is likely to occur; probability
an unpredicted event, esp a fortunate one: that was quite a chance, finding him here
(archaic) an unlucky event; mishap
by chance

accidentally: he slipped by chance
perhaps: do you by chance have a room?

chances are…, the chances are…, it is likely (that) …
on the chance, acting on the possibility; in case
the main chance, the opportunity for personal gain (esp in the phrase an eye to the main chance)
verb
(transitive) to risk; hazard: I’ll chance the worst happening
to happen by chance; be the case by chance: I chanced to catch sight of her as she passed
chance on, chance upon, to come upon by accident: he chanced on the solution to his problem
chance one’s arm, to attempt to do something although the chance of success may be slight
n.
v.

chance it
chance on