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.
Patent pending. Patent pending (sometimes abbreviated by pat. pend. or pat. pending) or patent applied for are legal designations or expressions that can be used in relation to a product or process once a patent application for the product or process has been filed, but prior to the patent being issued or the application abandoned.