DuckCorp Dico

Found one definition

1.                 From WordNet (r) 3.0 (2006):
                   
   
   
                   
                     
   pH
       n 1: (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); [syn: pH, pH scale]