Soil, land, and the globe
In current English, earth is still first of all matter: soil that can grow a crop, dirt on a spade, the dry surface as against sea or sky. Capitalized, Earth is the planet. The same noun also names this life as opposed to heaven, a fox’s or badger’s hole, and, in British electrical usage, a connection driven into the ground. Those jobs look scattered. They are later applications of one inherited word for what you stand on.
The origin of the word earth is native. English did not take it from Latin terra or French terre. It inherited a Germanic noun that is already there in Old English, in the period before 1150.
An English word from the start
Middle English wrote erthe, with a crowd of local spellings: erþe, eorthe, yerth, urthe, and others. All of them continue Old English eorþe, a feminine noun. Anglo-Saxon use covered soil and dirt, dry land as opposed to water, a country or district, and the material world of human life, set against the heavens and the underworld. In that last sense eorþe overlapped with middangeard, the middle dwelling later English readers meet as Middle-earth.
Nothing in that history is a loan into English. The Old English form comes from Proto-West Germanic erþu, from Proto-Germanic erþō, reconstructed as dirt, ground, earth. The same noun appears across the family: Old Frisian erthe, Old Saxon ertha, Dutch aarde, Old High German erda and modern German Erde, Old Norse jörð and its descendants Icelandic jörð and Swedish and Danish jord, Gothic airþa. Scots yird and related forms are the same word kept in the north, not a later import.
Translators did lean on this native stock. Early English often used earth where Latin had terra and where Anglo-Norman and French had terre, because those languages bundled similar ideas: soil, land, world, inhabitants. Contact of that kind can stretch a word’s range. It does not make earth a Romance borrowing.
Root, extension, and what is not proven
English earth has no living prefix or suffix. The extra piece is older. Handbooks of Indo-European roots treat the Germanic form as a t-extension of a root meaning earth or ground. The spelling of that root is not uniform. Some lists write er-. Others, working with laryngeals, write something like h₁érteh₂. The Oxford English Dictionary ties the Germanic noun to the same extended base that gives Old High German ero and a Greek adverb meaning toward the ground. Other extensions sometimes grouped with it include a Germanic word for sand or soil and Welsh erw, a measure of land.
That deeper layer is a reconstruction, not a recorded form, and the details are argued. Proposed cousins farther afield, such as Latin ōra for an edge or Hittite erḫaš for a border, are less secure than the Germanic set. Look-alikes in other families are usually treated as chance. The Semitic noun behind Arabic arḍ and Hebrew ereṣ sounds close and means something similar; most etymologists still keep it apart. Another well-known Indo-European word for earth, the root behind Latin humus and Greek khthōn, is a different item. English earth does not come from it, and Latin terra itself is yet another formation, from a root connected with dryness.
Dutch aarde, the cognate of earth, is the first half of aardvark, earth pig. The compound is a useful check: the old meaning is soil and ground, not a named planet.
From underfoot to overhead
The physical core never left. Soil, land, and the surface you walk on are still the ordinary uses. What grew was the scale.
Old English already paired heaven and earth in biblical and poetic language for the created world. Some late Old English scientific prose even treats the earth as a body in the middle, with the sun moving above and below it. Modern dictionaries often date the planetary sense, the world as a sphere among other bodies, to around 1400. That date marks when the astronomical reading becomes ordinary in English, not the first time learned writers thought of the ground as a world. Sources do not line up on a single first year; the safer claim is a slow widening from soil and land to globe.
From the late fourteenth century the noun also served as a verb: to earth a corpse was to bury it, to put it into the ground. Hunters kept earth for an animal’s den. Eighteenth-century chemistry used earths for certain oxides that would not melt easily and would not dissolve in water; alkaline earths still carry that fossil. British electrical earth is the same picture as American ground: a path into the soil. None of these is a new root. Each is the old ground-word given a new task.
What receded is earth as a stretch of country, a district you could name. Land, country, and world took more of that work. What remained, beside dirt and planet, is the contrast with heaven: on earth still means in this life, not in another.
The same noun next door
A short way to hold the history is to look at German Erde or Dutch aarde. They are not loans from English, and English is not a loan from them. All three are one Germanic noun that started as dirt and ground and later named the globe. The planet kept the farmer’s word.