The definition of pH is:
pH = -log 10[H^+]
what is the defintion of the [OH^-]...
is it pOH = -log 10[OH^-]?
Yes!!
pH = - log10 anything.
pKa = -log Ka
Pkb = -log Kb
pKw = -log Kw = 14
PKsp = -log Ksp (solubility product)
and so on into the night.