Hypertrichosis: an abnormal amount of hair growth on the body relative to the amount normally present on a person of the same age, race, and gender. Hypertrichosis has also been referred to as Ambras Syndrome and informally as Werewolf syndrome. The degree of severity can vary among affected persons. The excess hair may be present in one area of the body or all over the body and may be fine or thick, short or long. It is sometimes associated with other abnormalities. The condition can be either present at birth (congenital) or may develop later in life (acquired). Causes range from genetic abnormalities to medical conditions including cancer and metabolic disorders. Hypertrichosis may also result as a side effect of certain drugs. In some cases, the cause is unknown.