Entry 1 sense Webster, 1913 Septuagenarian /sĕp-cho͞oˌ-əj-ən-ĕr'-ē-ən/ · Sep·tu·a·ge·na·ri·an · IPA /ˌsɛptəd͡ʒɪˈnɛɹiən/ 01 n. A person who is seventy years of age; a septuagenary. 1. A person who is seventy years of age; a septuagenary.