Dead to the world' is an idiom that means someone is completely UNAWARE of their surroundings, either due to sleep or unconsciousness. The crossword solutions for this term include 'ASLEEP' (6 letters), 'COMATOSE' (8 letters), 'INERT' (5 letters), 'UNCONSCIOUS' (11 letters), 'OUT' (3 letters), 'UNAWARE' (7 letters), and 'passedout' (9 letters). All of these words describe a state of being in which someone is not conscious or aware of their environment.