(from potential of Hydrogen) the logarithm of the reciprocal of hydrogen-ion concentration in gram atoms per liter; provides a measure on a scale from 0 to 14 of the acidity or alkalinity of a solution (where 7 is neutral and greater than 7 is more basic and less than 7 is more acidic)(Freq. 7) • Syn: pH scale • Topics: chemistry, chemical science • Hypernyms: hydrogen ion concentration • Hyponyms: acidity, alkalinity, neutrality