Toluidine Blue is a histological stain commonly used to diagnose various diseases. However, there are different types of toluidine blue that are often called by different names. For instance, some laboratories may refer to it as Basic Blue 17, or T-Blue, while others might know it as N-benzyl p-toluenesulfonamide. Toluidine Blue is a basic dye that stains acidic tissues and cells, making it an essential tool in cytology and histopathology. Besides these common synonyms, Toluidine Blue can also be referred to as Tolonium Chloride, Violet Cresyl Sulfuric Acid, and Methyl Violet. Knowing these various synonyms can help researchers and doctors to communicate effectively when using the dye.