Pronunciation: (ak"si-den'tl),[key] —adj. 1. happening by chance or accident; not planned; unexpected: an accidental meeting. 2. nonessential; incidental; subsidiary: accidental benefits. 3. Music.relating to or indicating sharps, flats, or naturals.
—n. 1. a nonessential or subsidiary circumstance, characteristic, or feature.
2. Music.a sign placed before a note indicating a chromatic alteration of its pitch.