accidental

modif.

1. Happening by chance

   chance, fortuitous, coincidental, unintentional, inadvertent, unplanned, unpremeditated, undesigned, unwitting, uncalculated, unintended, unanticipated, unforeseen, unexpected, casual, adventitious, random, haphazard, involuntary, lucky, unlucky, serendipitous, fluky*; see also unexpected.

2. Incidental

   incidental, secondary, nonessential, adventitious; see subordinate, under 3.

accidental describes that which occurs by chance an accidental encounter or outside the normal course of events an accidental attribute; fortuitous, which frequently suggests a complete absence of cause, now usually refers to chance events of a fortunate nature; casual describes the unpremeditated, random, or irregular quality of something a casual remark, a casual visit or its informality casual clothes; incidental emphasizes the nonessential or secondary nature of something incidental expenses; adventitious refers to that which is added extrinsically and connotes a lack of essential connection