There are several synonyms for the term "agent fill". Some of the most common synonyms include "filler", "extender", "thickener", "adulterant", and "diluent". These words are used to describe substances that are added to products or materials to increase their volume or bulk. For example, in the food industry, fillers are used to enhance the texture and volume of certain foods. Similarly, in the cosmetics industry, thickening agents are added to products to give them a thicker consistency. Overall, the use of agent fills is an important aspect of many industries, and the availability of synonyms for this term makes it easier for people to communicate effectively about the materials they are working with.