It is any substance that eliminates the impurity from the upper part of the body. Etiology
It is the study of the causes of all diseases. In ayurveda the cause of most of the diseases is due to the overuse, misuse or no use of the five senses.
That which eliminates the impurity from the upper part of the body is known as an Emetic. Some emetic herbs in Ayurveda are: Yashtimadhu, sugarcane juice. These are herbs that cause vomiting and have been used in the past in conditions characterized by a great deal of mucus (dispel kapha with vamana), to clear the mucus from the body. In modern herbalism, used to cause forceful emptying in cases of poisoning. Western herb examples: Ipecacuanha.