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.
DEFINITION of 'Patent'. A government license that gives the holder exclusive rights to a process, design or new invention for a designated period of time. Applications for patents are usually handled by a government agency.In the U.S. the United States Patent and Trademark Office handles application and documentation.Next Up. government license that gives the holder exclusive rights to a process, design or new invention for a designated period of time. Applications for patents are usually handled by a government agency. In the U.S. the United States Patent and Trademark Office handles application and documentation. Next Up.