Definition of: pH

Chem.
Denoting the negative logarithm of the hydrogen-ion concentration, in grams per liter, of a solution: used in expressing relative acidity and alkalinity. Thus, the ρH of pure water is 7, indicating a concentration of 10^–7, or 0.0000001 gram per liter, usually regarded as neutral. Decreasing acidity means decreasing hydrogen-ion concentration, or a rise in the absolute value of ρH. [<P(OTENTIAL OF) H(YDROGEN)]