Appendage and Affix

Appendage noun - Something that is not necessary in itself but adds to the convenience or performance of the main piece of equipment.

Affix is a synonym for appendage in attachment topic. In some cases you can use "Affix" instead a noun "Appendage", when it comes to topics like addition, add-on.

Nearby Words: append, appended, appending

Affix noun - A linguistic element added to a word to produce an inflected or derived form.

Appendage is a synonym for affix in add-on topic. You can use "Appendage" instead a noun "Affix".

Nearby Words: affixed, affixing, affixation