Noun
anything that happens suddenly or by chance without an apparent cause
Source: WordNetwinning the lottery was a happy accident Source: Internet
the pregnancy was a stroke of bad luck Source: Internet
it was due to an accident or fortuity Source: Internet
And even in those that he was successful this would be temporary, just until a mistake or chance event caused another failure, another disappointment for the frustrated duck. Source: Internet
The many negative findings suggest that either the trigger varies, or that it might in fact be a chance event inherent with the immune response. citation Half of the risk for RA is believed to be genetic. Source: Internet