Etymology
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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.

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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."

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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.

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good (n.)
Old English god (with a long "o"), "that which is good, a good thing; goodness; advantage, benefit; gift; virtue; property;" from good (adj.). Meaning "the good side" (of something) is from 1660s. Phrase for good "finally, permanently" attested from 1711, a shortening of for good and all (16c.). Middle English had for good ne ylle (early 15c.) "for good nor ill," thus "under any circumstance."
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good (adj.)
Origin and meaning of good

Old English gōd (with a long "o") "excellent, fine; valuable; desirable, favorable, beneficial; full, entire, complete;" of abstractions, actions, etc., "beneficial, effective; righteous, pious;" of persons or souls, "righteous, pious, virtuous;" probably originally "having the right or desirable quality," from Proto-Germanic *gōda- "fitting, suitable" (source also of Old Frisian god, Old Saxon gōd, Old Norse goðr, Middle Dutch goed, Dutch goed, Old High German guot, German gut, Gothic goþs). A word of uncertain etymology, perhaps originally "fit, adequate, belonging together," from PIE root *ghedh- "to unite, be associated, suitable" (source also of Sanskrit gadh- "seize (booty)," Old Church Slavonic godu "favorable time," Russian godnyi "fit, suitable," Lithuanian goda "honor," Old English gædrian "to gather, to take up together").

Irregular comparative and superlative (better, best) reflect a widespread pattern in words for "good," as in Latin bonus, melior, optimus.

Sense of "kind, benevolent" is from late Old English in reference to persons or God, from mid-14c. of actions. Middle English sense of "holy" is preserved in Good Friday. That of "friendly, gracious" is from c. 1200. Meaning "fortunate, prosperous, favorable" was in late Old English. As an expression of satisfaction, from early 15c. Of persons, "skilled (at a profession or occupation), expert," in late Old English, now typically with at; in Middle English with of or to. Of children, "well-behaved," by 1690s. Of money, "not debased, standard as to value," from late 14c. From c. 1200 of numbers or quantities, "large, great," of time or distance, "long;" good while "a considerable time" is from c. 1300; good way "a great distance" is mid-15c.

Why then, can one desire too much of a good thing. ["As You Like It"]

As good as "practically, virtually" is from mid-14c.; to be good for "beneficial to" is from late 14c. To make good "repay (costs, expenses), atone for (a sin or an offense)" is from late 14c. To have a good mind "have an earnest desire" (to do something) is from c. 1500. Good deed, good works were in Old English as "an act of piety;" good deed specifically as "act of service to others" was reinforced early 20c. by Boy Scouting. Good turn is from c. 1400. Good sport, of persons, is from 1906. The good book "the Bible" attested from 1801, originally in missionary literature describing the language of conversion efforts in American Indian tribes. Good to go is attested from 1989.

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big deal (n.)
from 1860s as "a good deal, a large amount;" by 1878 in financial speculation, originally in California publications; see deal (n.1). As an ironic expression, popular in American English from c. 1965, perhaps a translated Yiddishism (such as a groyser kunst).
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good-natured (adj.)
1570s, from good nature "pleasing or kind disposition" (mid-15c.), from good (adj.) + nature (n.). Related: Good-naturedly.
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good den 
salutation, Elizabethan corruption of good e'en, itself a contraction of good even "good evening," which is attested from c. 1500, first as gud devon, showing a tendency toward misdivision. See good (adj.) + even (n.).
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good-neighbor (adj.)
also (chiefly British English) good-neighbour, adjectival phrase, in reference to U.S. foreign policy, especially in Latin America, 1928, originally in Herbert Hoover. The good neighbours is Scottish euphemism for "the fairies" (1580s).
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good-looking (adj.)
"attractive, of pleasing appearance," 1742; see good (adj.) + look (v.). Good looks (n.) "attractive appearance" is attested from 1712.
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