Ego death is the experience of the self dissolving. The boundary that normally separates "me" from "everything else" softens, melts, or vanishes entirely, and what remains is a perspective without a central character — awareness without an owner. In its more intense forms the person reports the complete cessation of the sense of being a separate someone, often accompanied by a sense of unity, presence, awe, or (for some) terror.
The term is slippery because it travels through several different traditions that do not always agree on what they mean by it.
Where the term comes from
Carl Jung used "ego death" in a psychoanalytic sense: a necessary collapse of the old self-concept as a precondition for psychological rebirth. In this reading it is not literally the end of the self, but the end of the current version of the self, so that a more integrated one can take its place.
Timothy Leary, Ralph Metzner, and Richard Alpert borrowed the language in The Psychedelic Experience (1964), mapping it onto the Tibetan Book of the Dead as a stage encountered during high-dose psilocybin and LSD sessions. In that book, ego death is presented as the first bardo, the initial loosening of the familiar self that precedes the rest of the journey.
Contemplative traditions have been describing strikingly similar experiences for a lot longer. Advaita Vedanta calls it the recognition of atman as brahman. Theravada Buddhism frames it through anatta, or non-self. Certain strands of Sufism call it fana, annihilation in the divine. Christian mystics from Meister Eckhart to Teresa of Ávila described their own versions of unio mystica. The vocabulary differs, but the phenomenology reported across centuries and continents is surprisingly convergent.
What neuroscience is starting to say
Modern psychedelic research, especially at Johns Hopkins and Imperial College London, has begun to characterise ego death more precisely. Neuroimaging under psilocybin shows reduced activity and decreased internal coupling in the default mode network — the web of brain regions that normally constructs the narrative self, time-travels into autobiographical memory, and rehearses the future. When the default mode network goes quiet, the sense of being a unified, persistent "I" located behind the eyes can temporarily collapse. What takes its place is often described as unity, presence, boundarylessness, or a radical first-person equivalence with the rest of existence.
Clinically, the quality of an ego-dissolution experience is one of the strongest predictors of therapeutic benefit in psychedelic-assisted therapy for depression, addiction, and end-of-life anxiety. But it is not always pleasant. On the threshold it can manifest as a bad trip, a dark night of the soul, or a full existential crisis — and meditation practitioners report similar destabilising episodes at certain stages of long retreats.
What it might actually be
Ego death is not quite the destruction of the self so much as the discovery that the self was always a process, a verb, a continuously-rebuilt construction — and finding the machinery paused. The reports that come back from the other side of it are almost uniformly hard to translate into ordinary language, which is why the traditions that describe it lean so heavily on paradox, poetry, and negation. You do not so much have an ego-death experience as survive one, and carry back something that slightly reshapes what you thought you were.