h₂erh₃-
“to plough, to till”plough, till, earth
Root for ploughing, yielding Latin arare, Greek aroun, Old English erian, English ear (of corn).
Discussion
The PIE root *h₂erh₃- (to plough, to till the earth) is one of the most archaeologically diagnostic words in the reconstructed vocabulary: its presence in PIE confirms that the proto-speakers practised agriculture, not merely pastoralism. The root produced both the verb for ploughing and the noun for the plough itself.
Latin arāre (to plough) continues the root directly and gave English: arable (land suitable for ploughing), and the technical term aration. The Latin noun arātrum (plough — from *h₂erh₃-tro-, with the instrumental suffix *-tro- marking a tool) is one of the most perfectly preserved PIE tool-words.
Greek aróō (ἀρόω, "I plough") and the nominal derivative árotron (ἄροτρον, "plough") continue the root in the Hellenic branch. The word ároura ("ploughed land, field") appears in Homer as a standard measure of agricultural land.
Old English erian (to plough) preserves the native Germanic reflex, though the word became archaic in English, displaced by the Scandinavian-influenced plough (from ON plógr). The related Old English earþ (earth) may be connected to this root through the concept of "the ploughed thing" — the earth as the substance that receives the plough — though this etymology is debated (most scholars derive earth from *h₁er-, a different root).
Lithuanian árti (to plough) and Old Church Slavonic orati (to plough) confirm the Balto-Slavic reflexes.
The tool-word *h₂erh₃-tro- (plough) with the *-tro- suffix is structurally parallel to *h₂eḱs-lo- (axle) and *kʷekʷlo- (wheel) — the same suffix that produced nouns for technological implements. The plough, the wheel, and the axle: three PIE tool-words that define the technological horizon of the proto-culture. The plough in particular connects PIE to the early agricultural societies of the Pontic-Caspian steppe, where evidence for both grain cultivation and pastoral herding has been found in the archaeological record of the 4th millennium BCE.
Notes
Pokorny 62-63. English arable, Latin arvum (field).