The word "homeworld" referred to the planet, or in some cases moon, on which a particular species originated. For example, Earth was the homeworld of Earth Reptiles, such as Silurians, and humanity. (TV: Doctor Who and the Silurians) Gallifrey was the homeworld of the Time Lords, (TV: The Time Warrior) and Skaro was the homeworld of the the Thals and Kaleds, later the Daleks. (TV: Genesis of the Daleks)