What is the origin of tellurian?
The adjective and noun tellurian ultimately derive from the Latin noun tellūs (inflectional stem tellūr-) “ground, dry land, earth, the earth.” In English the adjective tellurian, meaning pretty much the same as terrestrial, was a technical term used in astronomy. Tellurian used as a noun, “an inhabitant of earth, earthling,” appears in the first half of the 19th century. Throughout much of the 20th century, tellurian, adjective and noun, occurs especially in science fiction. Tellūs comes from a Proto-Indo-European root tel– “flat, level, floor, ground,” the root of Sanskrit tala– “flat surface, flat of the hand”; Old Irish talam “earth”; Old Prussian (an extinct Baltic language) talus “floor (of a room)”; and Greek tēlía “board for rolling dice on, kitchen board.” Tellurian entered English in the second half of the 18th century.