The Collaborative International Dictionary of English v.0.48:

Pomptine \Pomp"tine\, a.
   See Pontine.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pontine \Pon"tine\, a. [L. Pontinus or Pomptinus, an appellation
   given to a district in Latium, near Pometia.]
   Of or pertaining to an extensive marshy district between Rome
   and Naples. [Written also Pomptine.]
   [1913 Webster]