The quality or state of being accidental or happening by chance rather than by design.
From accidential (Medieval Latin 'accidentialis') plus the suffix -ity (Latin '-itas'). This abstract noun allows philosophers to discuss 'the state of being accidental' as a concept.
This is the kind of twelve-letter word that only medieval theologians and modern physicists love—it's how Aristotle's followers debated whether the universe had to exist exactly as it does, or just happens to.
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