noun
A person who believes that events occur (either generally, or in a particular context) as a result of chance or contingency rather than viewing them as preordained or attributable to a single definite cause.
adjective
Designating a theory or belief that events occur as the result of chance or contingency; of or relating to such a theory or belief.
Origin
Early 19th century; earliest use found in Morning Watch. From accidental + -ist.
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