|accessary or accessory||
Accessary is a noun, usually used in British criminal law, which describes someone who helps another person commit a crime.
For example: "He was charged as an accessary to murder.."
Accessory is a noun, used to describe something that can be added to a machine or to clothing, which has a useful or decorative purpose.
For example: "An old outfit can be revamped with a simple new accessory."
!Note - In the USA, accessory is the spelling for both senses.