from Salon to Saloon.

French salon—from Middle French, from Italian salone (large hall), augmented form of Italian sala (hall), from Lombardic sala (room, house, entrance hall), from Proto-Germanic *salą (dwelling, house, hall), from Proto-Indo-European *sel- (human settlement, village, dwelling). Cognate with Old High German sal (room, house, entrance hall), Old English sæl (room, hall, castle), Old Church Slavonic селó (seló, courtyard, village), Lithuanian sala (village)—either augmentative of salle (room), or borrowed from Italian salone (hall), augmentative form of sala, salla (room); in both cases borrowed from a Germanic source such as Old High German sal (house, hall), from Proto-Germanic *salą, from Proto-Indo-European *sol-, derived from *sel- (dwelling).

Essentially, in its attempt to mimic French culture, the Old West mistranslated the French Salon to Saloon.