Source : Webster's Revised Unabridged Dictionary (1913)

Peloponnesian \Pel`o*pon*ne"sian\, a. [L. Peloponnesius, fr.
   Peloponnesus, Gr. ?, lit., the Island of Pelops; ?, ?, Pelops
   + ? an island.]
   Of or pertaining to the Peloponnesus, or southern peninsula
   of Greece. -- n. A native or an inhabitant of the
   Peloponnesus.

Source : WordNet®

Peloponnesian
     adj : of or relating to Peloponnesus; "Peloponnesian War"