The Chinese word 密室 is a compound noun formed by combining two meaningful characters: 密 (mì), which means "secret", "dense", or "closely guarded", and 室 (shì), which means "room" or "chamber". Together, they create a new concept meaning "secret room" or "hidden chamber", where the first character modifies the second to specify the type of room, one that is private, concealed, or inaccessible, often used in contexts like escape rooms (密室逃脱), mystery novels, or secure private spaces.