Accident

An accident is something going wrong unexpectedly. Physical examples include an unintended collision (including a person or object unintendedly falling, getting injured by touching something sharp, hot, electrically live, ingesting poisons, or getting injured by not properly landing when jumping. Non-physical examples are unintendedly revealing a secret or otherwise saying something stupid, forgetting an appointment, and similar events.
Technically, "accidents" do not include incidents where someone is at fault, i.e., negligent: where someone fails to take reasonable precautions under the circumstances. If the results of such negligence were foreseeable, they were certainly not "accidental" at that level, and the negligent person can be held liable for damages and personal injuries. In an "accident", there is simply nobody to blame, because the event was unforeseeable or very unlikely. For example, a pharmacist negligently mixes the wrong chemicals and mislabels them for sale; a person ingesting the chemicals according to the label instructions has been "accidentally" poisoned, but the pharmacist's mistake was not so accidental as much as it was negligent.
A common misconception is that a gun can "go off" accidentally, where in truth, such gun accidents are extremely rare, and most gun injuries are caused by intentional acts that create the hazard of injury (i.e., pulling the trigger of a loaded gun). A defective gun that fires when dropped could qualify as being "accidental", however, one would still have to examine the cause for the gun being intentionally loaded and being handled carelessly.
50,425 people were killed by "accidents" (not including car accidents) in the U.S. in 1995. That's 19 people in 100,000.
Often accidents are investigated so that we can learn how to avoid them in the future. This is sometimes called root cause analysis, but does not generally apply to accidents that cannot be predicted with any certainty. For example, a root cause of a purely random incident may never be identified, and thus future similar accidents remain "accidental."

Work Accident

An accident at work is defined as an external, sudden, unexpected, unintended, and violent event, during the execution of work or arising out of it, which causes damage to the health of or loss of the life of the employee (the insured).
For qualification as an accident at work to apply, there must be a causal relationship (direct or indirect relationship of cause and effect) between the violent event and the work. Only if the accident is due to "wilful misrepresentation" on the part of the employer or the employer's appointed representative is the employer under an obligation to compensate the victim. Under U.S. law, injured workers are often compensated according to the type of injury, rather than permitting them to sue the employer for the actual damages.
There is a significant proportion of work accidents occurring in the merchant marine.

Bicycle Accidents

Biker crushed by truck

A bicycle accident, an incident in which a bicycle ride goes wrong, can result in injury to the rider or another person in their path, and damage to the bicycle or nearby objects. In 1842, an accident occurred that has been described as the earliest bicycle accident. Kirkpatrick McMillan, the inventor of the velocipede (an early bicycle), rode his new invention for 40 miles (64 km) from his home to Glasgow. On his approach to the city, crowds gathered on the road and, unfortunately, Kirkpatrick collided with a young girl.
Although she was only slightly injured, he was subsequently charged with causing the first-ever bicycle accident. The judge could not believe Kirkpatrick had travelled the 40 miles to Glasgow in only five hours, but after much explaining, he was allowed to return home.
According to a study conducted in 2000 by SWOV (Institute for Road Safety Research) in the Netherlands, single bicycle accidents accounted for 47% of all bicycle accidents, collisions with obstacles and animals accounted for 12%, and collisions with other road users accounted for 40% (with the remaining 1% having unknown or unclassified cause).

Nuclear Accidents

Some incidents are called accidents even if they are not accidental. The Chernobyl accident for example occurred when technicians disabled the safety system and violated a long list of safe operating procedures. The resultant explosion has been termed an "accident", even when it was clearly caused by intentional acts meant to undermine the stable operation of the plant. Such are not accidents within the literal meaning of the word, but by constant repetition, may become known as accidents.