An '''[[w: | ]]''' is a specific, unpredictable, unusual and unintended external action which occurs in a particular time and place, with no apparent and deliberate cause but with marked effects. It implies a generally negative outcome which may have been avoided or prevented had [[w:Attendant circumstance|circumstances]] leading up to the accident been recognized, and acted upon, prior to its occurrence. However, an unexpected boon may also be referred to as a "happy accident".
