Dry matter refers to the solid content of a sample after removing all the water. There are several synonyms for dry matter, including solid matter, non-aqueous matter, and dehydrated material. Solid matter refers to any material that has no liquid or gas, making it different from liquids and gases. Non-aqueous matter, on the other hand, refers to substances that do not contain water. Dehydrated material refers to materials that have gone through a process of removing water. These are just a few examples of synonyms for dry matter, and knowing these can help in understanding scientific terms and discussions.