Alizarin crimson is a polysemic term, and here are its two meanings: Firstly, alizarin crimson is a widely used aniline red pigment, also known as 221 purple-red powder. It is primarily used for coloring coatings, inks, paints, leather, rubber, plastics, latex products, building materials, printing inks, stationery, and cosmetics. With a broad application range, it is an important pigment in many industries. Secondly, alizarin crimson can also refer to rhodamine B, a bright peach red synthetic basic fluorescent dye, also known as rose red B or basic rose essence. Rhodamine B is mainly used in laboratory cell fluorescence stains, dyes, the paper industry, manufacturing paints and pigments, and can also be used for dyeing fabrics and leather products. However, rhodamine B has certain toxicity and genotoxicity, and international research institutions classify it as a Class 3 carcinogen, indicating that its carcinogenicity to humans is可疑.