Definition of "Tellurian"

If any distant world (which may be the case) are so far ahead of us Tellurians in optical resources as to see distinctly through their telescopes all that we do on earth, what is the grandest sight to which we ever treat them?

1847, Thomas de Quincey, “Joan of Arc”, in Miscellaneous Essays

There is a mystery in Tellus which has not been solved. I cannot reconcile the disappearance of all its water and its race of men as well, with the legend preserved in our family that, not so very long ago, Tellurians visited us, staying beneath this very roof as guests. Why did the Earth-race die out so quickly?

1930 February, Edwards Gawain [pseudonym; George Edward Pendray], “A Rescue From Jupiter”, in Science Wonder Stories, volume 1, number 9, page 787

But it's well that that bunch of tellurians are dead! Our diamond was the cause of that much good for the earth!" Nega slowed her orbital speed, oscillated a bit, and twinkled: "Are all tellurians like those we've met in the last year?"

1935 May, Joseph William Skidmore, “A Saga of Posi and Nega”, in T[homas] O’Conor Sloane, editor, Amazing Stories, volume 10, New York, N.Y.: Teck Publishing Corporation, page 107

Mr. Bridges is more interested in correct usage of planetary names, rather than in mere derivations (a more useful and less frivolous involvement than mine, you see) and, for instance, advocates what he maintains to be correctly derived words such as Venustian and Hesperian for hypothetical inhabitants of Venus in place of the incorrect Venusian or Cytherean; and Tellus and Tellurian in place of Terra and Terran. He lists astronomers and classical scholars who support his views.

1965 December, Isaac Asimov, “Water, Water, Everywhere—”, in The Magazine of Fantasy and Science Fiction, volume 29, number 6 (number 175 overall), page 87