NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,798 terms related to cancer and medicine.

Browse the dictionary by selecting a letter of the alphabet or by entering a cancer-related word or phrase in the search box.

narcotic
(nar-KAH-tik)
A substance used to treat moderate to severe pain. Narcotics are like opiates such as morphine and codeine, but are not made from opium. They bind to opioid receptors in the central nervous system. Narcotics are now called opioids.