term:

Accident

accident n

:

an unexpected usually sudden event that occurs without intent or volition although sometimes through carelessness, unawareness, ignorance, or a combination of causes and that produces an unfortunate result (as an injury) for which the affected party may be entitled to relief under the law or to compensation under an insurance policy see also unavoidable accident NOTE: The term accident has been held to include intentional acts (such as an assault and battery) under workers’ compensation laws.
ac·ci·den·tal adj

ac·ci·den·tal·ly
also
ac·ci·dent·ly

adv