General:
* Fillers: This is a broad term that can be used for anything that fills a space.
* Separators: This word emphasizes the function of keeping things apart.
* Distancers: This is a less common term, but it can be useful to emphasize the distance created.
Specific:
* Shims: Used for adjusting gaps between surfaces, often made of thin metal.
* Bushings: Used in mechanical applications to reduce friction and wear.
* Gaskets: Used to seal gaps and prevent leaks.
* Insulators: Used to prevent the transfer of heat or electricity.
* Padding: Used to provide cushioning and protection.
To give you a more precise answer, please tell me what kind of spacers you are referring to. For example:
* Are they for mechanical applications?
* Are they used in construction?
* Are they used in electronics?
Once I know the context, I can give you a more relevant synonym for "spacers."