The quality of being accidental or unintentional; the state of happening by chance.
From accidental + -ness (Old English suffix creating abstract nouns). More common than accidentality in modern English.
The 'accidentalness' of great discoveries—penicillin, X-rays, post-it notes—shows that sometimes the best innovations come from happy accidents rather than careful planning, which is deeply comforting for clumsy inventors.
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