Tellurian is a variant spelling of tellurion, an instrument that depicts how day, night and the seasons are caused by the movement of the Earth on its axis and around the sun; it is similar to an orrery.

A Tellurian is also someone or something inhabiting the planet Earth. The concept of being a Tellurian is the ideological notion of a small, yet growing number of people who prefer to refer to themselves as such, instead of citizens of their nation or members of their religion in order to emphasize the idea of equality on a borderless and unified planet.