noun

• (pharmacology) A synthetic opioid narcotic analgesic C₂₂H₂₈N₂O with pharmacological action similar to morphine that is administered transdermally as a skin patch and in the form of its citrate C₂₂H₂₈N₂O·C₆H₈O₇ is administered orally or parenterally (as by intravenous or epidural injection); N-phenyl-N-[1-(2-phenylethyl)piperidin-4-yl]propanamide.