Adjective
Of a thing, event, etc., no longer used or available; unknown to or forgotten by everyone.
Of a person, no longer existent, deceased.
Of a person, physically located in a remote place where one is unnoticed or incommunicado.
Of a person, mentally focused on one's own thoughts or feelings, or on some task, to such a degree that one is unaware of other people or of one's surroundings; unconscious.