The word 地下 is formed through the direct spatial combination of its two component characters: 地 (dì), meaning "earth" or "ground", and 下 (xià), meaning "below" or "under". Conceptually, the character for "below" is placed immediately after the character for "ground", visually and logically constructing the idea of "the area that is beneath the ground surface", hence signifying "underground" or "below ground".