Noun

1. A twentieth-century philosophical movement emphasizing the uniqueness of each human existence in freely making its self-defining choices, with foundations in the thought of Soren Kierkegaard (1813-55) and Friedrich Nietzsche (1844-1900) and notably represented in the works of Karl Jaspers (1883-1969), Gabriel Marcel (1887-1973), Martin Heidegger (1889-1976), and Jean-Paul Sartre (1905-80).

   The heyday of existentialism occurred in the mid-twentieth century.

2. The philosophical views of a particular thinker associated with the existentialist movement.

   Sartre's existentialism is atheistic, but the existentialism of Marcel is distinctly Christian.

   • 1965, Mikel Dufrenne, "Existentialism and Existentialisms," Philosophy and Phenomenological Research, vol 26 no 1 (Sep), p. 51.

     Instead of Existentialism, we should speak of Existentialisms.