In the most recent episode of Anglophenia (previously), host Siobhan Thompson explains why Brits and Americans use different words for the same piece of clothing. Included in the list are fanny packs/bum bags, vests/waistcoats, sweaters/jumpers, sneakers/trainers, and, of course, trouser/pants. The accompanying article “British/American Clothing Confusion” on Anglophenia‘s sister site, Mind the Gap, explains the origin of the trouser/pants difference.
This is perhaps the most famous discrepancy of all Anglo/American nomenclature. Brits use “pants” as a generic term for men’s undergarments while, of course, in the U.S. the word is interchangeable with “trousers.” The word “pants” comes from the Middle French pantalon, meaning “a kind of tights,” which ultimately derived from the Italian pantalone, which was the local nickname for a Venetian man, who presumably wore tight-fitting trousers.