1) Colog 
In chemistry, a decimal cologarithm is indicated by the letter p. This usage originated with the quantity pH, defined as –log10 [H3O+]. Based on pH, the quantity pK was later defined as –log10 K. ...
the logarithm of the reciprocal of a number, often used in expressing the logarithm of a fraction: log = log 7 + colog 25. Symbol: colog