"Earth" may be used to describe two different concepts:
- The word earth (always written in the lower case) is a common noun which may refer to the dry surface of the world, land, ground, or underground (e.g. The soft earth is full of rich soil or Look where the earth and the sky meet). Narnian gnomes living underground were therefore called "Earthmen".
- Earth, The Earth or Planet Earth (always capitalised) is a proper noun that refers to the specific world from which the human race originates.