the.com/depersonalization

means A dissociative state in which you feel detached from your own body, thoughts, or self — like an observer of your own existence rather than a participant in it.

from Built from the Latin-rooted 'person' (from persona, the mask an actor wore in ancient theater to project a character) plus 'de-', undoing or removing. So, etymologically, it's the stripping away of the mask — or the self behind it. The term entered psychiatric vocabulary in the late 19th century, as clinicians in France and elsewhere began describing patients who felt estranged from their own identity, as though the 'person' had been peeled off, leaving only the watching.