Table 1 Existing definitions of existential loneliness

Moustakas ([21], p. 24)

“Existential loneliness is an intrinsic and organic reality of human life in which there is both pain and triumphant creation emerging out of long periods of desolation. In existential loneliness man is fully aware of himself as an isolated and solitary individual while in loneliness anxiety man is separated from himself as a feeling and knowing person.”

Yalom ([20], p. 221)

“An existential loneliness which […] extends far beyond ordinary social loneliness; it is the loneliness of being separated not only from people but from the world, as one ordinarily experiences it, as well.”

Mayers et al. ([29], p. 1184)

“A third form of loneliness, existential loneliness, has been defined as a primary and inevitable condition of existence (Burton, 1961; Mijuskovic, 1977; Moustakis, 1961) for which no permanent remedy can be found. Proponents of this form of loneliness believe that since all humans are born into a world where perfect communication with others is impossible and only death is certain, a basic sense of loneliness emerges.”

Ettema et al. ([13], p. 142)

“An intolerable emptiness, sadness, and longing, that results from the awareness of one’s fundamental separateness as a human being”

Bolmsjö et al. ([9], p. 1315, 1322)

“A feeling of being fundamentally separated from others and the world”

“EL can be understood as the immediate awareness of being fundamentally separated from other people and from the universe, primarily through experiencing oneself as mortal, or, and especially when in a crisis, experiencing not being met (communicated with) at a deep human (i.e., authentic) level, and typically therefore experiencing negative feelings, that is, emotions or moods, such as sadness, hopelessness, grief, meaninglessness or anguish.”

Larsson et al. ([34], p. 1624)

“A basic sense of loneliness that occurs when we, as human beings, face that we are separated and alone in the world despite having other people around”

van Tilburg ([6], p. e335)

“Existential loneliness stems from the realization that a human being is fundamentally alone, with the accompanying emptiness, sadness, and longing.”

Fried (2019) in Prohaska et al. ([35], p. 277)

“Existential loneliness describes feeling separate from other people and society – a void within, and being aware of one’s own mortality, e.g. a sense of longing that cannot be sated through any type of social interaction; despite solid relationships, the person still feels empty.”