the Latin word for "earth, the earth," from PIE root *ters- "to dry." It is found as a qualifying adjective in various phrases from Latin and Italian (terra); e.g. terrae filius (1580s) "man of unknown origin," literally "son of the earth."
Also compare terrene, terrestrial. The range of adjectives and derived nouns attempted from it in English testifies to the range of what "earth" can be: an "element" in old science (as opposed to air, fire, water); solid ground and land (as opposed to the sea); the realm of worldly and mundane concerns (as opposed to the spiritual); and, in Modern English, a planet among planets (as opposed to Mars, Neptune).
Terrenal "terrestrial, earthly" was used mid 15c.-16c. Terrestre (mid-14c.-16c.) meant "earthly, of the earth," from Old French terrestre; hence terrestrihede (late 14c.) "quality of belonging to elemental earth, earthiness," and terrestrish "earthy" (early 15c.).
As a noun, terrestrite in medieval physiology was the combination of coldness and dryness characteristic of the element earth (early 15c. from Medieval Latin terrestritas "terrestrial, earthly"). The 17c. also tried as nouns terrenity "worldliness; quality or condition of being earthly" and terreity "essential quality of earth, earthiness." Terrosity "earthiness" is likewise obsolete.
In 16c. terrestrene, terrestrian also were tried. Expanding the vocabulary, T. Browne found terreous "earthy, consisting of earth;" terrestrious "of or belonging to earth or land."
Terrigenous "earth-born" is from 17c.; 19c. biology introduced terricolus "inhabiting the ground" (as opposed to aquatic, aerial), with Latin colere "inhabit;" also terricoline (1895, but apparently a dictionary word).
