The term RED DYE can refer to a variety of different substances, including HENNA (5 letters), MADDER (6 letters), EOSIN (5 letters), KERMES (6 letters), and EOSINE (6 letters). HENNA is a plant-based dye that has been used for centuries to dye skin, hair, and fabrics. MADDER is a red dye derived from the roots of the MADDER plant. Eosin is a synthetic dye used in histology and microscopy. Kermes is a red dye made from the dried bodies of female scale insects. Eosine is a synthetic dye used in biology and medicine.