Origins
Soup is a liquid food made by boiling or simmering meat, fish, vegetables, or legumes in stock or water, and it is one of the oldest forms of cooked food known to humans — the archaeological record shows soup-like preparations in the Levant and East Asia from at least the sixth millennium BCE. The English word soup, however, is quite young: it was borrowed from French soupe only in the seventeenth century. Before that, English had pottage, broth, browis, or sew (from Old English sēaw, juice) for what we now call soup. The French source soupe originally denoted not the liquid but the bread: a slice or sop of bread placed in a bowl over which broth was poured. That older meaning survives in English as sop and in the verb to sop up. The word travels from Germanic through Late Latin and back into Germanic: Late Latin suppa "bread soaked in broth" was itself borrowed from a Germanic source — compare Proto-Germanic *supô (something soaked, liquid food) — so that by the time English took soup back from French in the 1600s the word had already made a round trip.
The earliest layer of the family is the Proto-Germanic verb *sūpan- (to sip, to drink slowly), from Proto-Indo-European *seub- or *sewb- (to drink in, to absorb). From *sūpan- descend Old English sūpan "to drink, to sup," Old Norse súpa, Old High German sūfan, Dutch zuipen; and from the related noun *supô come Old English sopp (bread dipped in liquid), Old Norse soppa, Middle Dutch soppe. The modern English sup (to have supper), supper itself, sop, soppy, and (through Latinised Germanic) soup all belong to the same root family. Late Latin borrowed the Germanic noun as suppa in the early medieval period, and it spread rapidly through the Romance languages — Old French soupe (12th century), Provençal sopa, Italian zuppa, Spanish sopa, Portuguese sopa, Catalan sopa — all meaning, at first, a slice of bread saturated with broth rather than the broth itself. Medieval French menus distinguish the soupe (the sop) from the bouillon (the broth) from the potage (the whole dish).
English pottage, the older word soup displaced in polite speech, comes from Old French potage (from pot, "pot") and meant any thick dish boiled in a pot: in Esau's famous bargain in Genesis 25 (KJV, 1611) he sells his birthright "for a mess of pottage" — a phrase still proverbial in English. The word soup is first securely attested in English in the 1650s, in cookery writing such as Robert May's The Accomplisht Cook (1660) and Hannah Woolley's The Gentlewoman's Companion (1673). Samuel Johnson's Dictionary (1755) defines soup as "strong decoction of flesh for the table." By Mrs Beeton's Book of Household Management (1861) soup has become the dominant term, and an elaborate classificatory apparatus has grown up around it: clear soup, thick soup, cream soup, purée, bisque, consommé, broth, chowder, potage. French cuisine distinguishes soupe (generally rustic, with bread) from potage (finer, often bound with starch) from consommé (clarified), a terminological hierarchy that passed into English professional cooking and still governs restaurant menus.
Proto-Indo-European Roots
Cognates of the borrowed soupe are found throughout Europe: French soupe (source of the English loan), Italian zuppa (especially zuppa inglese, "English soup," the trifle-like dessert named in the nineteenth century either for its resemblance to English puddings or, according to one story, for the English diplomats who liked it at the ducal court of Parma), Spanish sopa, Portuguese sopa, Catalan sopa, Romanian supă, Dutch soep, German Suppe, Swedish soppa, Danish suppe, Norwegian suppe, Polish zupa, Russian суп (sup, borrowed from French in the Petrine period), Hungarian leves (native) but also zupa in older registers, Turkish çorba (unrelated). The Germanic cousins — German Suppe, Dutch soep, Swedish soppa — are in most cases reborrowings from French rather than direct survivals from Germanic *supô, which had largely been replaced by native words such as German Brühe (broth) before being displaced again by the French-mediated international term.
In modern English soup has spread metaphorically in several directions. Primordial soup, coined by J. B. S. Haldane and Alexander Oparin in the 1920s, describes the chemical broth from which life is theorised to have emerged. In the soup means to be in trouble, recorded from late-nineteenth-century American slang. Duck soup, US slang for "an easy task," dates to the 1900s. Soup kitchen (a place where soup is distributed to the destitute) is attested from the 1830s and became a fixture of Depression-era vocabulary. The soup du jour ("soup of the day") is a conventional French phrase in English-language restaurants. Meanwhile, the old cognate sop — in the technical sense of bread dipped in broth — survives principally in the phrase "a sop to Cerberus" (a pacifying offering, from the drugged honeyed cake given to the three-headed hound of Hades in Virgil's Aeneid VI) and in the verb to sop up. The round trip of the word — Germanic to Latin, Latin to French, French to English, while an older Germanic sibling still sits beside it in the language — is one of the tidier examples of how cooking vocabulary traces the political and culinary exchanges of medieval and early-modern Europe.