NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,791 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.

acidity
(a-SIH-dih-tee)
Describes the amount of acid in a substance. An acid is a chemical that gives off hydrogen ions in water and forms salts by combining with certain metals. Acidity is measured on a scale called the pH scale. On this scale, a pH value of 7 is neutral, and a pH value of less than 7 to 0 shows increasing acidity.