Definition of "existentialism"

existentialism

/ˌɛɡzɪˈstɛnʃəlɪzəm/

noun
countable and uncountable, plural existentialisms
1. (philosophy, not countable) A twentieth-century philosophical movement emphasizing the uniqueness of each human existence in freely making its self-defining choices.
2. (philosophy, countable) The philosophical views of a particular thinker associated with the existentialist movement.
  Quotations
  Instead of Existentialism, we should speak of Existentialisms.
  1965 Sep, Mikel Dufrenne, “Existentialism and Existentialisms”, in Philosophy and Phenomenological Research, volume 26, number 1, page 51