h₂eyos-
“metal, copper, bronze”Source of Latin aes, English ore, era, esteem
Root for metal/copper/bronze, yielding Latin aes (bronze) and English ore, era (bronze age reckoning).
Discussion
The Proto-Indo-European root *h₂eyos- is reconstructed with the meaning "metal", likely referring to copper or bronze in the proto-language period. This root is significant for dating purposes: the existence of a word for metal suggests that the Proto-Indo-European community existed during or after the Chalcolithic period, when copper working was developing across Eurasia.
The most debated reflex is English iron, which descends from Old English īsern or īren. The Germanic forms (compare German Eisen, Gothic eisarn) are generally derived from a Celtic intermediary, and the ultimate connection to *h₂eyos- involves a complex chain of borrowing and sound change that not all scholars accept. Some linguists instead connect the Germanic iron words to an Illyrian or other non-Indo-European substrate. The question remains open.
English ore, meaning raw metal-bearing rock, is more securely connected to this root, descending from Old English ōra "unwrought metal, ore". Latin aes "copper, bronze" (genitive aeris) is the clearest Latin reflex, producing English words such as era (originally a counting unit related to copper coinage) and the chemical symbol for copper, Cu (from cuprum, itself from Cyprium aes "Cyprian metal").
Sanskrit áyas- "metal, iron" is a key cognate that preserves the original form closely, though the meaning shifted from copper to iron as metallurgical knowledge advanced — a semantic development paralleled in several branches. Avestan ayah- "metal" confirms the Indo-Iranian form.
The semantic shift from "copper/bronze" to "iron" in several branches independently reflects the technological transition from the Bronze Age to the Iron Age. The root *h₂eyos- thus encodes not just a word but a chapter of human technological history, documenting the moment when metal first became important enough to name.
Related Roots
English Words from *h₂eyos-
These modern English words descend from this root. Each page traces the full journey from PIE to present-day English.