adjective Pertaining to accident and not essence; thus, inessential; incidental; secondary. .mw-parser-output .defdate{font-size:smaller}
adjective Nonessential to something's inherent nature (especially in Aristotelian thought).
adjective Adjusted by one or two semitones, in temporary departure from the key signature.
adjective Occurring sometimes, by chance; occasional.
adjective Happening by chance, or unexpectedly; taking place not according to the usual course of things; by accident, unintentional.
The discovery was purely accidental.
adjective 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.
noun 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.