A vitiated appetite that craves what is unfit for food, as chalk, ashes, coal, etc.; chthonophagia.
The essential feature is the eating of one or more nonnutritive substances on a persistent basis for a period of at least 1 month. The typical substances ingested tend to vary with age. Infants and younger children typically eat paint, plaster, string, hair, or cloth. Older children may eat animal droppings, sand, insects, leaves, or pebbles.