lost to the world

adjective4

1. •
   Of a thing, event, etc., no longer used or available; unknown to or forgotten by everyone.

   • In those days there was a word "trashy," now almost lost to the world. My dear Aunt Charlotte used that epithet when, in her feminine way, she swore at people she did not like. — 1898
2. •
   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.

   • Bill had relapsed into a sort of waking dream. He sat frowning sombrely, lost to the world. — 1921
3. •
   Of a person, no longer existent, deceased.

   • He was a sympathiser to the poor, the suffering, and the oppressed; and by his death, one of England’s greatest writers is lost to the world. — 1870
4. •
   Of a person, physically located in a remote place where one is unnoticed or incommunicado.

   • We have trekked the veldt and been lost to the world for many months at a time — 1920