Definitions
1.AdjectivePertaining to accident and not essence; thus, inessential; incidental; secondary. .mw-parser-output .defdate{font-size:smaller}
2.AdjectiveNonessential to something's inherent nature (especially in Aristotelian thought).
3.AdjectiveAdjusted by one or two semitones, in temporary departure from the key signature.
4.AdjectiveOccurring sometimes, by chance; occasional.
5.AdjectiveHappening by chance, or unexpectedly; taking place not according to the usual course of things; by accident, unintentional."The discovery was purely accidental.; He was killed by an accidental gunshot.; accidental damage; accidental death; entirely accidental"
6.AdjectiveBeing a double point with two distinct tangent planes in 4-dimensional projective space.
7.NounA property which is not essential; a nonessential; anything happening accidentally.
8.NounThose 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.
9.NounA sharp, flat, or natural, occurring not at the commencement of a piece of music as the signature, but before a particular note.
10.NounPart of a text that has a mainly structural purpose, such as spelling, punctuation, or capitalization.