- noun a form of indigestion where the patient has a burning feeling in the stomach caused by too much acid forming there
- noun the proportion of acid in a substance
- Acidity is a measure of the strength of an acid measured on the scale of pH which goes from 1 (very acid) through 2 (acidity of lemon juice), 3 (apple juice) to 7 (neither acid nor alkaline), the pH of pure water. pH values greater than 7 refer to alkalis. Very few food-spoiling organisms will grow at a pH equal to or less than 2.
- noun the level of acid in a liquid
- one of the key elements of any wine, providing a sharpness and definition to the taste
- the level of acid found in soil. Acidity and alkalinity are shown according to the pH scale on which pH7 is neutral, numbers above 7 indicate alkalinity, and those below 7 indicate acidity.