Silicon oxide is a chemical compound with the formula SiO2. There are several synonyms for this compound that are commonly used in different contexts. Silica is the most commonly used synonym, while other names include silicon dioxide, quartz, and sand. The term silicic acid is also used to refer to various types of silicates that contain SiO2, such as orthosilicates, metasilicates, and pyrosilicates. In addition, the term silica gel refers to a form of silicon oxide that is used as a desiccant and adsorbent. These synonyms are often used in various industries such as electronic, pharmaceutical, and construction, where silicon oxide is an important material.