1. (a.) Happening by chance, or unexpectedly; taking place not according to the usual course of things; casual; fortuitous; as, an accidental visit.

2. (a.) Nonessential; not necessary belonging; incidental; as, are accidental to a play.

3. (n.) A property which is not essential; a nonessential; anything happening accidentally.

4. (n.) 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.

5. (n.) A sharp, flat, or natural, occurring not at the commencement of a piece of music as the signature, but before a particular note.

accessory accident accidentally accompanying addendum addition additional adjunct ado adscititious adventitious afloat afoot aleatory appendage appurtenance appurtenant ascititious auxiliary breve by-the-way casual casually causeless chance chancy circumstantial coincident coincidental collateral conditional contingency contingent crotchet current demisemiquaver dependent destinal dicey doing dominant dominant note double whole note eighth note enharmonic enharmonic note eventuating extra fatal fatidic flat fluky fortuitous fortuitously going on half note happening happenstance hemidemisemiquaver iffy in hand in the wind inadvertent incidental indeterminate inessential lucky mere chance minim musical note natural nonessential not-self note occasional occurring odd on on foot ongoing other parenthetical passing patent note prevailing prevalent provisional quarter note quaver random report responding note resultant risky secondary semibreve semiquaver serendipitous shaped note sharp sixteenth note sixty-fourth note spiccato staccato subsidiary superadded superaddition superfluous supervenient supplement supplemental supplementary sustained note taking place tercet thirty-second note tone triplet unanticipated uncalculated uncaused under way undesigned undetermined unessential unexpected unforeseeable unforeseen unintended unintentional unlooked-for unlucky unmeant unplanned unpredictable unpremeditated unpurposed unwitting whole note