From Longman Dictionary of Contemporary Englishbe dead to the worldbe dead to the worldUNCONSCIOUSSLEEPto be very deeply asleep or unconscious Better leave Craig – he’s dead to the world. → dead
Examples from the Corpus
be dead to the world• Anyway Amanda was dead to the world.• I'm sorry I didn't hear the phone -- I must have been dead to the world this morning. 