an event, usu of an unfortunate nature, occurring by chance or arising from unknown causes
lack of intention or necessity; chance
We met by accident rather than by design
an unexpected happening causing loss or injury
a non-essential property or condition of something
an irregularity of a surface, e.g. of the moon
[Middle English via French from Latin accident-, accidens non-essential quality, chance, present part. of accidere to happen, from ad- + cadere to fall]