Arsenious oxide is a chemical compound that is commonly used in various industrial and scientific applications. It is also known by several other names, including arsenic trioxide, arsenic(III) oxide, white arsenic, and arsenic sesquioxide. These synonyms are often used interchangeably to refer to the same substance. Arsenious oxide is a toxic compound that has been used historically as a pesticide and even as a poison. It has many other uses as well, such as in the manufacturing of glass and ceramics, in metallurgy, and in the production of pigments and dyes. The many different names for this compound reflect its diverse uses and properties.