derealisation

noun
  1. 1

    The psychological symptom in which the world appears to be unreal, and the patient has a sense of detachment from it.

  2. 2

    (The process of) making unreal, in general; detachment from reality or realness.

Source: https://en.wiktionary.org/wiki/derealisation, https://en.wiktionary.org/wiki/derealization