accident

noun

1. an undesirable or unfortunate happening that occurs unintentionally and usually results in harm, injury, damage, or loss; casualty; mishap: automobile accidents.
2. 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.
3. any event that happens unexpectedly, without a deliberate plan or cause.
4. chance; fortune; luck: I was there by accident.
5. a fortuitous circumstance, quality, or characteristic: an accident of birth.
6. Philosophy. any entity or event contingent upon the existence of something else.
7. Geology. a surface irregularity, usually on a small scale, the reason for which is not apparent.

noun

1. an unforeseen event or one without an apparent cause
2. anything that occurs unintentionally or by chance; chance; fortuneI met him by accident
3. a misfortune or mishap, esp one causing injury or death
4. Also called: adjunct logic philosophy a nonessential attribute or characteristic of something (as opposed to substance)
5. metaphysics a property as contrasted with the substance in which it inheres
6. geology a surface irregularity in a natural formation, esp in a rock formation or a river system

n.

late 14c., “an occurrence, incident, event,” from Old French accident (12c.), from Latin accidentem (nominative accidens), present participle of accidere “happen, fall out, fall upon,” from ad- “to” (see ad-) + cadere “fall” (see case (n.1)). Meaning grew from “something that happens, an event,” to “something that happens by chance,” then “mishap.” Philosophical sense “non-essential characteristic of a thing” is late 14c. Meaning “unplanned child” is attested by 1932.