accidental

Meanings

Adjective

• Not essential; incidental, secondary.
• Nonessential to something's inherent nature (especially in Aristotelian thought).
• Adjusted by one or two semitones, in temporary departure from the key signature.
• Occurring sometimes, by chance; occasional.
• Happening by chance, or unexpectedly; taking place not according to the usual course of things; by accident, unintentional.
• Being a double point with two distinct tangent planes in 4-dimensional projective space.

Noun

• A property which is not essential; a nonessential; anything happening accidentally.
• Those fortuitous effects produced by luminous rays falling on certain objects so that some parts stand forth in abnormal brightness and other parts are cast into a deep shadow.
• A sharp, flat, or natural, occurring not at the commencement of a piece of music as the signature, but before a particular note.
• Part of a text that has a mainly structural purpose, such as spelling, punctuation or capitalization.

Origin

• From Middle English accidental, from Anglo-Norman accidentel, Middle French accidentel, accidental, and their source, Late Latin accidēntālis; corresponding to accident + -al.