happening by chance or accident; not planned; unexpected

an accidental meeting.

nonessential; incidental; subsidiary

accidental benefits.

Music . relating to or indicating sharps, flats, or naturals.

a nonessential or subsidiary circumstance, characteristic, or feature.

Music . a sign placed before a note indicating a chromatic alteration of its pitch.

adjective

decided , designed , essential , intended , intentional , planned , premeditated

adjective

adventitious , casual , chance , coincidental , contingent , fluky * , fortuitous , inadvertent , incidental , random , uncalculated , unexpected , unforeseen , unintended , unintentional , unplannednotes:accidental stresses chance; fortuitous so strongly suggests chance that it often connotes absence of cause , fluky , odd , conditional , extraneous , extrinsic , haphazard , nonessential , secondary , serendipitous , subordinate , unplanned