Splitting, sharing, and striking a bargain
In current English, deal does more than one job. As a verb it can mean to distribute, to trade, to handle a difficulty, or to give someone a blow. As a noun it can mean a transaction, a bargain, an amount (a great deal of time), a round of cards, or the treatment someone receives. One further noun, the pine or fir board sold as deal, looks identical but is historically separate. The origin of the word deal for share, distribute, and bargain is native Germanic English: a pair of Old English forms whose first work was to name a part of a whole and the act of cutting that whole into portions.
Inherited, not borrowed from French
The main noun and verb did not enter English through Norman French. Old English already had dǣl for a part, share, or portion, and dǣlan for dividing, distributing, sharing, or taking part in something. Middle English carried them forward as del, dele, and delen. The modern spelling deal and the long vowel are later regularizations of those inherited forms.
Written English has the pair from the Old English period, before 1150, with attestations going back before 900. That dating matches a Common Germanic inheritance rather than a medieval loan. German Teil and teilen, Dutch deel and delen, West Frisian diel, Swedish del and dela, and Gothic dails sit in the same family. Old Frisian del could mean a part or a legal district; Old Norse deild named a share in a similar way. English kept a close relative in dole, from Old English dāl, another word for a portion. The verb is the noun made active: a Germanic verbal formation on the “part” stem, reconstructed as Proto-Germanic *dailijaną beside the noun *dailiz or *dailaz. When English still deals out shares or deals a pack of cards, that old morphology is still doing its original work.
A deeper root that sources do not settle
Beyond Germanic, the trail is less firm. Baltic and Slavic words for “part” and “divide” look related, among them Lithuanian dalis and dalinti and Slavic verbs such as Russian delit’. Some reconstructions set up a Proto-Indo-European *dail- “to divide,” sometimes treated as a northern extension of a simpler root *da- with the same meaning. Other accounts rebuild a different Indo-European shape, and some etymologists leave open the chance that the Germanic noun is a substrate word rather than a clean inheritance from Indo-European. Those deeper proposals should stay marked as uncertain. What is not in dispute is the Germanic layer and the Old English pair that English still uses.
How the senses moved
For a long stretch the noun did work that later English gave to part. A deal was a slice of a whole. By about 1200 it could also mean someone’s allotted share. With a qualifier such as great or good it named an extent or quantity rather than a physical cut: a great deal of difference, a good deal of money. That quantity sense is now the main everyday survival of the old “portion” noun. The unadorned meaning “a part of something” has largely gone obsolete.
The verb’s path is easier to follow because the older meanings stay visible. From “divide and distribute” it came to mean “hand someone their share,” recorded around 1300. From distribution in general came the card-table sense in the 1500s; the matching noun for a round of cards is in use by about 1600. To deal someone in, centuries later, still uses that dealing image for bringing a person into an undertaking.
To deal with someone or something, from the late fourteenth and fifteenth centuries, meant to have dealings, to handle a person or a matter, or to behave toward them in a particular way. One older use of the same phrase referred to sexual relations; that sense dropped away, while the handling and coping uses grew. Trade senses grew from the same cluster of “having to do with”: to deal in goods, to deal as a merchant, and much later the slang of selling illicit drugs. Inflicting a blow is another offshoot of giving someone their portion, this time an unwelcome one.
The business noun—a transaction or bargain—is late. It is recorded in 1837 as slang, built on an older idea of an arrangement among several people for mutual advantage. From that commercial sense come fair deal and raw deal as kinds of treatment, deal-breaker by the 1970s, and New Deal as a political slogan, used by Franklin D. Roosevelt in 1932 though the phrase itself is a few years older. Big deal as an important transaction appears in 1928; the sarcastic shrug is later, first noted in 1951.
A timber homonym
Late Middle English also took in dele from Middle Low German or Middle Dutch dele, a plank, especially of fir or pine. That word belongs with German Diele and with Old English þelu, “board, flooring,” not with dǣl. It is a homonym, not a later sense of “share.” The timber form is already visible in surnames from the late thirteenth century, and as a common noun it is established in the fourteenth. A deal desk and a business deal are therefore two different words that happen to share a spelling.
What the cognates still make obvious
German Teil still means “part,” and teilen still means “to divide.” English kept the verb busy—cards, trade, blows, problems—and let part take over most of the noun’s old territory, except in a great deal and in the bargain sense that nineteenth-century slang made central. The contract you strike today began as a cut of a whole.