- (metrology) Symbol for the picohenry, an SI unit of electrical inductance equal to 10−12 henrys.
- (chemistry) Measure of the acidity or basicity of an aqueous solution.
From p, denoting negative logarithm, and H, denoting hydrogen.
pH (plural pHs)
- (chemistry) The negative of the logarithm to the base 10 of the concentration of hydrogen ions, measured in moles per liter; a measure of acidity or alkalinity of a substance, which takes numerical values from 0 (maximum acidity) through 7 (neutral) to 14 (maximum alkalinity).