Mammoth Cave, the world's longest known cave system. The following is a list of the world's 10 longest caves per length of documented passageways. Many passageways are still being discovered; this list is based on the latest verifiable data.
patent medicine - medicine that is protected by a patent and available without a doctor's prescription. medicament, medication, medicinal drug, medicine - (medicine) something that treats or prevents or alleviates the symptoms of disease. nostrum - patent medicine whose efficacy is questionable.
What is a patent: protecting inventions and innovation. A patent is a monopoly right granted by a national or regional patent office to an inventor who has created something new, useful and non-obvious; e.g. an innovation in the pharmaceutical sector that results in a new headache pill or a new technology used in computer hardware.