From The Food Encyclopedia by Jacques Rolland and Carol Sherman
Also curcuma. A bright yellow rhizome from an Asian plant, Curcuma longa, from the Latin terra merita, meaning "deserving earth." The Greek physician Dioscorides mentioned it as a tonic to stimulate the appetite and as a cure for overeating and indigestion. Its powdered form was used well before the time of Christ as an economical alternative to saffron. In the Middle Ages, it was called "Indian saffron" and also used as a fabric dye, as it still is today. The ceremonial garments of monks from the Far East are dyed with turmeric. In India, a tincture based on turmeric is traditionally rubbed on the abdomen during labor and on the umbilical cord of the newborn baby as an antiseptic and for "golden" good luck. No Hindu celebration or gathering takes place without turmeric, ceremoniously and cosmetically, most notably at weddings. It's also one of the basic ingredients in Indian cooking. In the West Indies, turmeric is used to dye some margarines and dairy products. Unlike ginger, a related rhizome, which is often available fresh, turmeric is usually sold dried, as a powder, and is best stored in the dark, because it's sensitive to light.
