Emily Dickinson Lexicon

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

1. Acceding; contributing; aiding in producing some crime 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, articulatory sounds in music.