appendage

1. Something added or attached to an entity of greater importance or size; an adjunct.

2. Biology A part or organ, such as an arm, leg, tail, or fin, that is joined to the axis or trunk of a body.

Synonyms: These nouns denote subordinate elements added to another entity. An appendage supplements without being essential: " ... and the complete absence of appendages at the stern decreases hull resistance" (R.J.L. Dicker).
An appurtenance belongs naturally as a subsidiary attribute, part, or member: "an internationally known first-class hotel ... equipped with such appurtenances as computers, word processors, copiers and telex" (Oscar Millard).
An adjunct is added as an auxiliary but is often self-sustaining: "Intelligence analysts ... believe that of all the countries of the Middle East, none use terrorism more effectively as an adjunct to diplomacy ..." (Elaine Sciolino).
An accessory is usually nonessential but desirable: Our new car has such accessories as air conditioning and a sunroof.
An attachment adds a function to the thing to which it is connected: The food processor has an attachment for kneading dough.