A type of Maraṇa (death);
the death which is final with respect to a particular life-form, in which a Jīva dies after experiencing the Karma-pudgalas (material clusters qua Karma) of the Āyuṣya (life-span-determining) Karma, responsible for the present life; there is no return to that life-form again at any time in future.
ātyantikamaraṇaṃ yāni nārakādyāyuṣkatayā kar-madalikānyanubhūya mriyate mṛtaśca na punastānyanubhūya mariṣyati.
(Sama 17.9 Vṛ Pa 32)