Frankl defines the term “existential” as referring to the state of existing as a human being, the value and purpose of existence, or the will to meaning. In other words, existential problems are those that involve the question of what it means to be a human and to be alive. Frankl says that a man’s will to meaning can be hampered by “existential frustration,” which can in turn cause “noögenic neuroses.” Noögenic is a logotherapeutic term that comes from the Greek word noös, or “mind,” and refers to anything connected to “the dimension of human existence.”
Frankl applies terms to the phenomena he witnessed while living in concentration camps. A nöogenic neurosis might include the profound apathy the prisoners felt, because this apathy was brought about by existential frustration and a loss of the will to meaning.