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 'Medical Patent'. A legal protection against market competition that a government grants to the inventor of a unique medical item or process. patent prevents competitors from making, using or selling the patented item or process for a limited time. In the United States, the three categories of patents are utility patents, design patents and plant patents.