Acid dyes are a type of water-soluble dye that contain acidic groups such as sulfonic or carboxylic acid. These dyes are widely used in the textile industry to dye protein fibers like wool, silk, and nylon. Some synonyms for acid dye include acid coloring, acidic dyestuff, and acid chromogen. Another term for acid dye is anionic dye, which refers to their negatively charged nature. Acid dyes come in a variety of bright and vibrant colors, making them a popular choice for creating bold and striking designs on fabrics and textiles. Overall, acid dyes are an essential component of the textile industry.