The word "死宅" is formed by combining the character "死", meaning "death", which here functions as an intensifier to convey extremity or hardcore behavior, with the character "宅", meaning "house", which in modern slang refers to a person who predominantly stays at home, often engaged in activities like gaming or watching anime. The compound thus denotes someone who is an extreme homebody, with a negative connotation of excessive seclusion and social withdrawal.