Accidental

  1. adjective
    without intention (especially resulting from heedless action); "with an inadvertent gesture she swept the vase off the table"; "accidental poisoning"; "an accidental shooting"
  2. adjective
    associated by chance and not an integral part; "poetry is something to which words are the accidental, not by any means the essential form"- Frederick W. Robertson; "they had to decide whether his misconduct was adventitious or the result of a flaw in his
  3. adjective
    occurring or appearing or singled out by chance; "their accidental meeting led to a renewal of their friendship"; "seek help from casual passers-by"; "a casual meeting"; "a chance occurrence"
  4. noun
    a musical notation that makes a note sharp or flat or natural although that is not part of the key signature