Origins
The word 'denim' hides a city inside itself. It is a contraction of 'de Nîmes' — from Nîmes — naming one of the world's most ubiquitous fabrics after a city in southern France that most denim wearers have never heard of.
Nîmes (Roman Nemausus) is a city in the Languedoc region of southern France, about forty kilometers from the Mediterranean coast. It has been a center of textile production since Roman times, and its most famous export to the English language is a piece of itself: the 'de Nîmes' that became 'denim.'
The phrase 'serge de Nîmes' appears in French textile records from the seventeenth century, referring to a sturdy woven fabric produced in the city. 'Serge' is a type of twill weave (from Latin 'sērica,' silken, ultimately from Greek 'Sēres,' the Silk People — the Greek name for the Chinese). When the fabric was exported to England, the name was contracted: 'serge de Nîmes' became 'de Nîmes,' which English speakers further compressed to 'denim.' The process is a classic case of apocope — the loss of sounds from the end of a word — combined with foreign-name simplification.
Modern Usage
Historians have raised a complication, however. The original 'serge de Nîmes' may not have been the same fabric as modern denim. French textile records suggest it was a wool-silk blend, while the cotton twill weave we recognize as denim today was likely developed independently, possibly in northern Italy. The cotton fabric associated with work clothes and eventually with blue jeans may have multiple origins, with the Nîmes name attached to it after the fact or through confusion with a similar-looking product.
The companion word 'jeans' has a parallel geographic etymology. 'Jean' as a fabric name comes from 'Gênes,' the French name for Genoa (Italian 'Genova'), a major Mediterranean trading port where a sturdy cotton-linen fabric called 'jean fustian' was produced and exported. English sailors in the sixteenth century wore 'Genoese' trousers, shortened to 'jeans.'
So 'denim jeans' is etymologically 'Nîmes-fabric Genoa-trousers' — a garment whose name weaves together two Mediterranean cities, one French and one Italian, both with long textile traditions. The irony is that denim jeans became the quintessential American garment. Levi Strauss, a Bavarian-born immigrant to San Francisco, partnered with tailor Jacob Davis in 1873 to patent riveted denim work pants — the blue jeans that would become a global cultural icon. The most American piece of clothing in the world is named after two European cities and was invented by a German immigrant.
Latin Roots
The city of Nîmes itself has embraced its etymological legacy. A museum in the city traces the history of denim, and the tourist literature makes much of the connection. The city's ancient name, Nemausus, derives from a pre-Roman Gaulish word — possibly the name of a local spring deity — making the deepest layer of the word 'denim' not French, not Latin, but Celtic or pre-Celtic.