RhymeZone: accidentalism definitions

Definitions of accidentalism:

noun: Accidental character or effect.
noun: The belief that outward appearance often contrasts with substance or essence (after Thomas Aquinas).
noun: A system of medicine based on belief that symptoms of disease are caused by external factors.
noun: The belief that events happen by random chance, without cause or purpose.

(Definitions from Wiktionary)