noun

• (psychology) The psychological symptom in which the world appears to be unreal, and the patient has a sense of detachment from it.
  "Derealization frequently co-occurs with depersonalization disorder, in which affected individuals notice an altered perception of their surroundings, resulting in the world seeming unreal or dreamlike."
• (The process of) making unreal, in general; detachment from reality or realness.
  "The derealization of Arab Americans created the conditions whereby, after the attacks of 9/11, the American public was willing to allow, and sometimes become complicit in, their government's detention, extradition, and torture of Arabs and Muslims […]"