Deal
Old English dǣlan ‘divide’, ‘participate’, of Germanic origin; related to Dutch deel and German Teil ‘part’ (noun), also to dole1. The sense ‘divide’ gave rise to ‘distribute’, hence deal1 (sense 1 of the verb, sense 4 of the verb); the sense ‘participate’ gave rise to ‘have dealings with’, hence deal1 (sense 2 of the verb, sense 3 of the verb).
wiktionary
From Middle English del, dele, from Old English dǣl(“part, share, portion”), from Proto-Germanic *dailiz(“part, deal”), from Proto-Indo-European *dʰail-(“part, watershed”). Cognate with Scots dele(“part, portion”), West Frisian diel(“part, share”), Dutch deel(“part, share, portion”), German Teil(“part, portion, section”), Danish del(“part”), Swedish del ("part, portion, piece") Icelandic deila(“division, contention”), Gothic 𐌳𐌰𐌹𐌻𐍃( dails, “portion”), Slovene del(“part”). Related to Old English dāl(“portion”). More at dole.
From Middle English delen, from Old English dǣlan(“to divide, part”), from Proto-West Germanic *dailijan, from Proto-Germanic *dailijaną(“to divide, part, deal”), from Proto-Indo-European *dʰail-(“part, watershed”).
From Middle English dele(“plank”), from Middle Low German dele, from Old Saxon thili, ultimately from Proto-Germanic *þiljǭ(“plank, board”); cognate with Old English þille. Doublet of thill.
etymonline
deal (n.1)
"a part or portion," Middle English del, from from Old English dæl "a part of a whole, a share;" with qualification (great, etc.), "an extent, degree, quantity, amount," from Proto-Germanic *dailaz (source also of Old Norse deild, Old Frisian del "part; juridical district," Dutch deel, Old High German and German teil, Gothic dails "part, share, portion"), from PIE *dail- "to divide" (source also of Old Church Slavonic delu, Lithuanian dalis "part"), perhaps a Northern Indo-European extended form of the root *da- "to divide," or perhaps a substratum word.
Formerly used in many senses now taken by part. Meaning "a share (of something), one's allotted portion" is from c. 1200. Business sense of "transaction, bargain" is 1837, originally slang, from the older sense of "arrangement among a number of persons for mutual advantage." In American history, New Deal is from Franklin D. Roosevelt's speech of July 2, 1932 (the phrase itself is by 1834). Big deal is from 1928 as "important transaction;" ironic use first recorded 1951 in "Catcher in the Rye." Deal-breaker is attested by 1975.
deal (n.2)
"plank or board," especially of fir or pine, late 14c., dele, from Low German (compare Middle Low German dele), from Proto-Germanic *theljon." From late 13c. in surnames. An Old English derivative was þelu"hewn wood, board, flooring."
deal (v.)
Middle English delen, from Old English dælan "to divide, distribute, separate;" hence "to share with others, bestow, dispense," and also "take part in, have to do with," from Proto-Germanic *dailjanan (source also of Old Saxon deljan, Old Frisian dela "to divide, distribute," Middle Dutch, Dutch deelen, German teilen, Gothic dailjan),from PIE *dail- "to divide," perhaps a Northern Indo-European extended form of root *da- "to divide," or a word from a substrate language.
Meaning "to deliver (to another) as his share" is from c. 1300. Meaning "to distribute cards before a game" is from 1520s (the associated noun meaning "distribution of cards before a game" is from c. 1600). Hence colloquial deal (someone) in "include in an undertaking" (1942).
To deal with "handle, act toward (in some way)" is attested from mid-15c., from the notion of "engage in mutual intercourse, have to do with;" in late 14c. the phrase also mean "have sexual intercourse with." Related: Dealt; dealing.
