- A measure of the strength of an alkali on the scale of pH which goes from 7 (neutral) through 7.7 to 9.2 (egg white), 8.4 (sodium bicarbonate or baking soda), 11.9 (household ammonia) to 14 (highest value of alkalinity). Strong alkalis such as sodium hydroxide react with fat in the skin to form soaps which give a characteristic slimy feel.
- noun the level of alkali in a body
- the level of alkali found in soil. Alkalinity and acidity are shown according to the pH scale on which pH7 is neutral, numbers above 7 indicate alkalinity and those below 7 indicate acidity.