Existentiell (existenziell), 12-13, 267-270 (§ 54), 305-310 (§ 62), et passim; distinguished from the existential, 12-16, 325fn. See also existential; ontic (BT)

NT: Existentivo = existentiell: já Ser e Tempo introduz na Analítica do Dasein a distinção entre das existenziale e das existentielle. A primeira expressão se refere à estrutura ontológica da existência enquanto a segunda diz respeito às suas formas ônticas. Para traduzir essa última emprega-se o neologismo existentivo. (CartaH)

existenziell (existentiell). This Kierkegaardian spelling (almost: cf. GA61:182, where the Diederichs translation is already modified by the Heideggerian “z”) is used once in SS 1920, more frequently in Heidegger’s letter of August 1921 to his existentialist student Karl Lowith. But the adjective receives terminological sustenance first in Oct. 1922 (pp. 14f.), with the introduction of Existenz, understood as the most unique, i.e., “existentiell,” possibility of life’s facticity, into the core of Heidegger’s conceptual framework. It is first linked to the “ontic” side of Dasein in BT itself. (Kisiel, GHBT)