NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,863 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.

rapid-onset opioid
(… OH-pee-OYD)
A substance that acts quickly to treat moderate to severe pain. Opioids are like opiates, such as morphine and codeine, but are not made from opium. Opioids bind to opioid receptors in the central nervous system. A rapid-onset opioid is a type of alkaloid.