Medley and melee are etymological siblings — both descend from Old French meslee, the past participle of mesler (to mix), which traces back to Latin miscēre (to mix). The same root act of mixing produced, in English, a peaceful musical combination and a violent confused fight. The divergence reveals how context shapes meaning: mixing songs is pleasant; mixing combatants is chaos.
The word entered English through Anglo-French medlee in the 14th century, initially carrying both the sense of a mixture and the sense of a battle or confused combat. For several centuries, medley could mean a fight or brawl — a usage now entirely taken over by its sibling melee (borrowed later from the same French source with a different spelling).
By the 16th century, medley had begun specializing toward its current peaceful meanings. The textile sense — cloth woven from yarns of different colors — appeared early and reflects the literal idea of mixing. The musical sense, now the word's most prominent meaning, developed fully in the 17th century, describing a composition that strings together portions of different songs or musical themes.
The musical medley became a staple of popular entertainment. In the 18th and 19th centuries, operatic medleys allowed audiences to enjoy highlights from fashionable operas without sitting through complete performances. In the 20th century, medleys became fundamental to popular music — from vaudeville and Broadway to rock concert encores and DJ mashups.
The swimming medley — in which a single swimmer or relay team performs all four competitive strokes (butterfly, backstroke, breaststroke, freestyle) — adapts the word to athletics. The individual medley, introduced to Olympic competition in 1964, demands versatility that mirrors the word's own meaning: a mixing of different elements into a single performance.
The Latin root miscēre has produced an enormous family of English words: mix, miscellaneous, miscible, mestizo, mezcal, promiscuous (literally 'thoroughly mixed'), and miscreant (originally 'misbehaving,' from mixing badly). The root connects to Proto-Indo-European *meyḱ-, meaning to mix, which also produced Greek mignynai (to mix) and Sanskrit miśra (mixed).