an undesirable or unfortunate happening that occurs unintentionally and usually results in harm, injury, damage, or loss; casualty; mishap

automobile accidents.

Law . such a happening resulting in injury that is in no way the fault of the injured person for which compensation or indemnity is legally sought.

any event that happens unexpectedly, without a deliberate plan or cause.

chance; fortune; luck

I was there by accident.

a fortuitous circumstance, quality, or characteristic

an accident of birth.

Philosophy . any entity or event contingent upon the existence of something else.

Geology . a surface irregularity, usually on a small scale, the reason for which is not apparent.

noun

intent , intention , necessity , plan , provision , calculation , decision , decree

noun

blow , calamity , casualty , collision , crack-up , disaster , fender-bender , fluke * , hazard , misadventure , misfortune , mishap , pileup * , rear ender , setback , smash * , smashup * , stack-up , total * , wrack-up , adventure , circumstance , contingency , fate , fortuity , fortune , happening , luck , occasion , occurrence , turn , contretemps , mischance , fluke , hap , happenchance , happenstance , accidentality , act of god , case , catastrophe , chance , crash , curse , event , fatality , force majeure , hitch , holocaust , inadvertence , inadvertency , incident , serendipity , sorrow , tribulation , trouble , vicissitudes , vis major , wreck