AC'CESSORY, a. [L. Accessorius, from accessus, accedo. See Accede. This word is accented on the first syllable on account of the derivatives, which require a secondary accent on the third; but the natural accent of accessory is on the second syllable, and thus it is often pronounced by good speakers.]

1. Acceding; contributing; aiding in producing some effect, or acting in subordination to the principal agent. Usually, in a bad sense, as John was accessory to the felony.

2. Aiding in certain acts or effects in a secondary manner, as accessory sounds in music.


1. In law, one who is guilty of a felony, not by committing the offense in person or as principal, but by advising or commanding another to commit the crime, or by concealing the offender. There may be accessories in all felonies, but not in treason. An accessory before the fact, is one who counsels or commands another to commit a felony, and is not present when the act is executed; after the fact, when one receives and conceals the offender.

2. That which accedes or belongs to something else, as its principal.

Accessory nerves, in anatomy, a pair of nerves, which arising from the medulla in the vertebers of the neck, ascend and enter the skull; then passing out with the par vagum, are distributed into the muscles of the neck and shoulders.

Accessory, among painters, an epithet given to parts of a history-piece which are merely ornamental, as vases, armor, &c.