accessory
adjunct
ancillary
adjuvant
appurtenant
auxiliary
furnishing added support
an ancillary pump
an adjuvant discipline to forms of mysticism
The mind and emotions are auxiliary to each other
accessary
aiding and abetting in a crime
he was charged with being accessory to the crime
appurtenance
supplement
add-on
a supplementary component that improves capability
accoutrement
accouterment
clothing that is worn or carried, but not part of your main clothing
someone who helps another person commit a crime