What does accident mean?
The definition of accident
Ac”ci*dent, n.
Etym: [F. accident, fr. L. accidens, -dentis, p. pr. of accidere to happen; ad + cadere to fall. See Cadence, Case.]

1 Literally, a befalling; an event that takes place without one’s foresight or expectation; an undesigned, sudden, and unexpected event; chance; contingency; often, an undesigned and unforeseen occurrence of an afflictive or unfortunate character; a casualty; a mishap; as, to die by an accident. Of moving accidents by flood and field. Shak. Thou cam’st not to thy place by accident: It is the very place God meant for thee. Trench.
2 (Gram.)
A property attached to a word, but not essential to it, as gender, number, case.
3 (Her.)
A point or mark which may be retained or omitted in a coat of arms.
4 (Log.)

(a) A property or quality of a thing which is not essential to it, as whiteness in paper; an attribute.
(b) A quality or attribute in distinction from the substance, as sweetness, softness.

5 Any accidental property, fact, or relation; an accidental or nonessential; as, beauty is an accident. This accident, as I call it, of Athens being situated some miles from the sea. J. P. Mahaffy.
6 Unusual appearance or effect. [Obs.] Chaucer.

Note: Accident, in Law, is equivalent to casus, or such unforeseen, extraordinary, extraneous interference as is out of the range of ordinary calculation.