Source : Webster's Revised Unabridged Dictionary (1913)

Accessory \Ac*ces"so*ry\, n.; pl. {Accessories}.
   1. That which belongs to something else deemed the principal;
      something additional and subordinate. ``The aspect and
      accessories of a den of banditti.'' --Carlyle.

   2. (Law) Same as {Accessary}, n.

   3. (Fine Arts) Anything that enters into a work of art
      without being indispensably necessary, as mere ornamental
      parts. --Elmes.

   Syn: Abettor; accomplice; ally; coadjutor. See {Abettor}.

Accessory \Ac*ces"so*ry\ (#; 277), a. [L. accessorius. See
   {Access}, and cf. {Accessary}.]
   Accompanying as a subordinate; aiding in a secondary way;
   additional; connected as an incident or subordinate to a
   principal; contributing or contributory; said of persons and
   things, and, when of persons, usually in a bad sense; as, he
   was accessory to the riot; accessory sounds in music.

   Note: Ash accents the antepenult; and this is not only more
         regular, but preferable, on account of easiness of
         pronunciation. Most orho["e]pists place the accent on
         the first syllable.

   Syn: Accompanying; contributory; auxiliary; subsidiary;
        subservient; additional; acceding.

Source : WordNet®

accessory
     adj : relating to something that is added but is not essential;
           "an ancillary pump"; "an adjuvant discipline to forms
           of mysticism"; "The mind and emotions are auxilliary to
           each other" [syn: {adjunct}, {ancillary}, {adjuvant}, {appurtenant},
            {auxiliary}, {subsidiary}]

accessory
     n 1: clothing that is worn or carried, but not part of your main
          clothing [syn: {accoutrement}, {accouterment}]
     2: a supplementary component that improves capability [syn: {appurtenance},
         {supplement}, {add-on}]
     3: someone who helps another person commit a crime [syn: {accessary}]