leþer

Old English leþer comes from Proto-Germanic *leþrą, of uncertain ultimate origin. Some scholars connect it to Old Irish lethar (leather) and suggest a Celtic borrowing. Others propose a connection to Proto-Indo-European roots meaning 'to peel' or 'to strip.' The etymology is debated. What is certain is that the word is old, the material is older, and the process of turning animal skin into a durable, flexible material has been practiced for at least 7,000 years.

Tanning — the chemical process that converts raw hide into leather — is one of humanity's oldest technologies. Vegetable tanning uses tannins from bark and plant matter. Chrome tanning, introduced in 1858, uses chromium salts and is faster but produces toxic waste. The word 'tanning' itself comes from medieval Latin tannāre, possibly from Celtic tann (oak tree), because oak bark was the primary tanning agent. The tree tanned the hide. The hide became leather.

Leather was ubiquitous before synthetics. Shoes, belts, saddles, armor, book bindings, furniture, bags, garments, water containers, parchment (a form of untanned leather) — the material was everywhere because it was available everywhere animals were kept. The word 'leather' named something so common it was barely noticed. The leather worker's guild was in every medieval town.

The ethical and environmental critique of leather has changed the word's connotation. Vegan leather (usually polyurethane or polyester), lab-grown leather, mushroom leather — each defines itself against animal leather. The word 'leather' now requires a modifier: genuine leather, real leather, full-grain leather. The unmarked default — the animal skin that was simply called 'leather' for millennia — has become a position that requires defending.