Entry 1 sense Webster, 1913 Peloponnesian /pĕlˌ-əp-ən-ēzh'-ən/ · Pel·o·pon·ne·sian · IPA /pˌɛləpənˈiːʒən/ 01 a. Of or pertaining to the Peloponnesus, or southern peninsula of Greece. 1. Of or pertaining to the Peloponnesus, or southern peninsula of Greece.