Polysilicic acid is an inorganic compound that is commonly used as an intermediate in the production of pure silica. Some synonyms for polysilicic acid include silicic acid polymer, polymeric silicic acid, and silica gel. Other terms used to describe this compound include poly(silicic acid), silicon oxide hydrate, and silicic acid polycondensate. These terms are often used interchangeably to describe the same chemical compound. Polysilicic acid is used in a variety of applications, including water treatment, electronics, and the production of ceramics. It is also used as a binder and filler in the manufacturing of concrete and other construction materials.