Homeopathy is a medical system based on the belief that the body can cure itself. Those who practice it use tiny amounts of natural substances, like plants and minerals. They believe these stimulate the healing process. It was developed in the late 1700s in Germany. It’s common in many European countries, but it’s not quite as popular in the United States.

Merriam-Webster Online Dictionary
homeopathy (noun)
a system of medical practice that treats a disease especially by the administration of minute doses of a remedy that would in larger amounts produce in healthy persons symptoms similar to those of the disease