Earthly Cares

I'm reading Neil DeGrasse Tyson's "The Pluto Files", about the rise and fall of the ninth planet (or is it?), and early on he presented me with a fact I did not know: like various other elements named after the planets, the elements tellurium and selenium, which are in the same column of the periodic table and therefore have some properties in common, are named after the Earth and the moon, respectively.

I like that. Paired in the solar system and on the periodic table. But "tellurium" struck me as odd, because I knew that the usual Latin word for "earth" or "Earth" was "terra", so where did "tellurium" come from? Could it be that the "-ll-" had been transformed into "-rr-", or vice versa? It seemed unlikely but not impossible, because those sounds are so very close together in the mouth that lots of foreign speakers of English have a great deal of trouble not only distinguishing them but learning how to pronounce them.

The facts are even more interesting. Latin had two words for Earth: "tellus" and "terra". They are not one and the same: the one did not emerge from the other, though "tellus" is apparently older. The word "terra" may have originated from a corruption of the Latin phrase "tersa tellus", "dry land".

I said above that "terra" was the usual Latin word, and I said so because it's the one that gave English so many offshoots and compounds. "Terrarium", a collision between "terra" and "aquarium", is a dry aquarium, one with a little piece of land inside rather than a little ocean. "Terrestrial" means "earthly", "terrace" a platform built on a bed of earth, "terrain" the expanse of earth before you, "terra-cotta" literally "cooked earth", a kind of pottery made of fired or baked clay. "Terra" and its descendants originate from Indo-European "ters-", "dry", because dry land is not the ocean.

"Tellus", on the other hand, comes from IE "tel-", "flat, ground, floor, board", the root of hardly any English words, surprisingly enough. I did track down one for you, though: "title", which as I once said originally came from Latin "titulus" and meant "superscription": the "tel-" connection is the signboard on which this superscription or title was written.