c. 1200, "body of persons living under a religious discipline," from Old French ordre "position, estate; rule, regulation; religious order" (11c.), from earlier ordene, from Latin ordinem (nominative ordo) "row, line, rank; series, pattern, arrangement, routine," originally "a row of threads in a loom," from Proto-Italic *ordn- "row, order" (source also of ordiri "to begin to weave;" compare primordial), which is of uncertain origin. Watkins suggests it is a variant of PIE root *ar- "to fit together," and De Vaan finds this "semantically attractive."
The original English word reflects a medieval notion: "a system of parts subject to certain uniform, established ranks or proportions," and was used of everything from architecture to angels. Old English expressed many of the same ideas with endebyrdnes. From the notion of "formal disposition or array, methodical or harmonious arrangement" comes the meaning "fit or consistent collocation of parts" (late 14c.).
Meaning "a rank in the (secular) community" is first recorded c. 1300. Sense of "a regular sequence or succession" is from late 14c. The meaning "command, directive" is first recorded 1540s, from the notion of "that which keep things in order." Military and honorary orders grew out of the fraternities of Crusader knights.
The business and commerce sense of "a written direction to pay money or deliver property" is attested by 1837; as "a request for food or drink in a restaurant" from 1836. In natural history, as a classification of living things next below class and next above family, it is recorded from 1760. Meaning "condition of a community which is under the rule of law" is from late 15c.
In order "in proper sequence or arrangement" is from c. 1400; out of order "not in proper sequence or orderly arrangement" is from 1540s; since 20c. principally mechanical, but not originally so ("and so home, and there find my wife mightily out of order, and reproaching of Mrs. Pierce and Knipp as wenches, and I know not what," - Pepys, diary, Aug. 6, 1666).
Phrase in order to "for the purpose of" (1650s) preserves etymological notion of "sequence." In short order "without delay" is from 1834, American English; order of battle "arrangement and disposition of an army or fleet for the purposes of engagement" is from 1769. The scientific/mathematical order of magnitude is attested from 1723.
"being but a single unit or individual; being a single person, thing, etc. of the class mentioned;" as a pronoun, "a single person or thing, an individual, somebody;" as a noun, "the first or lowest of the cardinal numerals; single in kind, the same; the first whole number, consisting of a single unit; unity; the symbol representing one or unity;" c. 1200, from Old English an (adjective, pronoun, noun) "one," from Proto-Germanic *ainaz (source also of Old Norse einn, Danish een, Old Frisian an, Dutch een, German ein, Gothic ains), from PIE root *oi-no- "one, unique."
Originally pronounced as it still is in only, atone, alone, and in dialectal good 'un, young 'un, etc.; the now-standard pronunciation "wun" began c. 14c. in southwest and west England (Tyndale, a Gloucester man, spells it won in his Bible translation), and it began to be general 18c. Its use as indefinite pronoun was influenced by unrelated French on and Latin homo.
Before the name of a person, indicating "hitherto unknown" or not known to the speaker.
One and only "sweetheart" is from 1906. Slang one-arm bandit for a type of slot machine is recorded by 1938. One-night stand is 1880 in performance sense; 1963 in sexual sense. One of the boys "ordinary amiable fellow" is from 1893. One-track mind "mind capable of only one line of thought or action" is by 1915. Drinking expression one for the road is from 1950 (as a song title). One-man band is by 1909 in a literal sense, 1914 figurative. One of those things "unpredictable occurrence" is from 1934.
The conscience clause is one of the weaknesses of the Bill. It is one of those things which tend to create the bitterness. The conscience clause is one of those things which are inseparable from a Bill like this. It is one of those things which divides the sheep from the goats—members can pick them out for themselves—in the playground, in the school. ["Religious Exercises in School Bills," New Zealand Parliamentary Debates, Aug. 13, 1926]
elementary intransitive verb of motion, Old English cuman "to move with the purpose of reaching, or so as to reach, some point; to arrive by movement or progression;" also "move into view, appear, become perceptible; come to oneself, recover; arrive; assemble" (class IV strong verb; past tense cuom, com, past participle cumen), from Proto-Germanic *kwem- (source also of Old Saxon cuman, Old Frisian kuma, Middle Dutch comen, Dutch komen, Old High German queman, German kommen, Old Norse koma, Gothic qiman), from PIE root *gwa- "to go, come."
The substitution of Middle English -o- for Old English -u- before -m-, -n-, or -r- was a scribal habit before minims to avoid misreading the letters in the old style handwriting, which jammed them together. The practice similarly transformed some, monk, tongue, worm. Modern past tense form came is Middle English, probably from Old Norse kvam, replacing Old English cuom.
Meaning "to happen, occur" is from early 12c. (come to pass "happen, occur" is from 1520s). As an invitation to action, c. 1300; as a call or appeal to a person (often in expanded forms: "come, come," "come, now"), mid-14c. Come again? as an off-hand way of asking "what did you say?" is attested by 1884. For sexual senses, see cum.
Remarkably productive with prepositions (NTC's "Dictionary of Phrasal Verbs" lists 198 combinations); consider the varied senses in come to "regain consciousness," come over "possess" (as an emotion), come at "attack," come on (interj.) "be serious," and come off "occur, have some level of success" (1864). Among other common expressions are:
To come down with "become ill with" (a disease), 1895; come in, of a radio operator, "begin speaking," 1958; come on "advance in growth or development," c. 1600; come out, of a young woman, "make a formal entry into society," 1782; come round "return to a normal state or better condition," 1841; come through "act as desired or expected," 1914; come up "arise as a subject of attention," 1844; come up with "produce, present," 1934.
To have it coming "deserve what one suffers" is from 1904. To come right down to it "get to fundamental facts" is from 1875.
1756, "special vocabulary of tramps or thieves," later "jargon of a particular profession" (1801). The sense of "very informal language characterized by vividness and novelty" is by 1818.
Anatoly Liberman writes here an extensive account of the established origin of the word from the Northern England noun slang "a narrow piece of land running up between other and larger divisions of ground" and the verb slanger "linger, go slowly," which is of Scandinavian origin (compare Norwegian slenge "hang loose, sling, sway, dangle," Danish slænge "to throw, sling"). "Their common denominator seems to be 'to move freely in any direction' " [Liberman]. Noun derivatives of these (Danish slænget, Norwegian slenget) mean "a gang, a band," and Liberman compares Old Norse slangi "tramp" and slangr "going astray" (used of sheep). He writes:
It is not uncommon to associate the place designated for a certain group and those who live there with that group’s language. John Fielding and the early writers who knew the noun slang used the phrase slang patter, as though that patter were a kind of talk belonging to some territory.
So the sense evolution would be from slang "a piece of delimited territory" to "the territory used by tramps for their wandering," to "their camping ground," and finally to "the language used there." The sense shift then passes through itinerant merchants:
Hawkers use a special vocabulary and a special intonation when advertising their wares (think of modern auctioneers), and many disparaging, derisive names characterize their speech; charlatan and quack are among them.
[Slang] is a dialectal word that reached London from the north and for a long time retained the traces of its low origin. The route was from "territory; turf" to "those who advertise and sell their wares on such a territory," to "the patter used in advertising the wares," and to "vulgar language" (later to “any colorful, informal way of expression”).
[S]lang is a conscious offence against some conventional standard of propriety. A mere vulgarism is not slang, except when it is purposely adopted, and acquires an artificial currency, among some class of persons to whom it is not native. The other distinctive feature of slang is that it is neither part of the ordinary language, nor an attempt to supply its deficiencies. The slang word is a deliberate substitute for a word of the vernacular, just as the characters of a cipher are substitutes for the letters of the alphabet, or as a nickname is a substitute for a personal name. [Henry Bradley, from "Slang," in Encyclopedia Britannica, 11th ed.]
A word that ought to have survived is slangwhanger (1807, American English) "noisy or abusive talker or writer."
"terminal part of the leg of a vertebrate animal," Old English fot "foot," from Proto-Germanic *fōts (source also of Old Frisian fot, Old Saxon fot, Old Norse fotr, Danish fod, Swedish fot, Dutch voet, Old High German fuoz, German Fuß, Gothic fotus "foot"), from PIE root *ped- "foot." Plural form feet is an instance of i-mutation.
The linear measure was in Old English (the exact length has varied over time), this being considered the length of a man's foot; a unit of measure used widely and anciently. In this sense the plural is often foot. The current inch and foot are implied from measurements in 12c. English churches (Flinders Petrie, "Inductive Metrology"), but the most usual length of a "foot" in medieval England was the foot of 13.2 inches common throughout the ancient Mediterranean. The Anglo-Saxon foot apparently was between the two. All three correspond to units used by the Romans, and possibly all three lengths were picked up by the Anglo-Saxons from the Romano-Britons. "That the Saxon units should descend to mediæval times is most probable, as the Normans were a ruling, and not a working, class." [Flinders Petrie, 1877]. The medieval Paul's Foot (late 14c.) was a measuring standard cut into the base of a column at the old St. Paul's cathedral in London. The metrical foot (late Old English, translating Latin pes, Greek pous in the same sense) is commonly taken to represent one rise and one fall of a foot: keeping time according to some, dancing according to others.
In Middle English also "a person" (c. 1200), hence non-foot "nobody." Meaning "bottom or lowest part of anything eminent or upright" is from c. 1200. Of a bed, grave, etc., from c. 1300. On foot "by walking" is from c. 1300. To get off on the wrong foot is from 1905 (the right foot is by 1907); to put one's best foot foremost first recorded 1849 (Shakespeare has the better foot before, 1596); Middle English had evil-foot (adv.) "through mischance, unluckily." To put one's foot in (one's) mouth "say something stupid" is attested by 1942; the expression put (one's) foot in something "make a mess of it" is from 1823. To have one foot in the grave "be near death" is from 1844. Colloquial exclamation my foot! expressing "contemptuous contradiction" [OED] is attested by 1923, probably euphemistic for my ass in the same sense, which dates to 1796 (also see eyewash).
parting salutation, 1860, of unknown origin, perhaps from a German idiom (compare German parting salutation adieu so lange, the full sense of which probably is something like "farewell, whilst (we're apart)"); or perhaps from Hebrew shalom (via Yiddish sholom). Some have noted a similarity to Scandinavian leave-taking phrases, such as Norwegian Adjø så lenge, Farvel så lenge, Mor'n så lenge, literally "bye so long, farewell so long, morning so long;" and Swedish Hej så länge "good-bye for now," with så länge "for now" attested since 1850 according to Swedish sources. Most etymology sources seem to lean toward the German origin. So long (adv.) "for such a long time" is from late Old English.
Earlier guesses that it was a sailors' corruption of a South Pacific form of Arabic salaam are not now regarded as convincing. "Dictionary of American Slang" also adds to the list of candidates Irish slán "safe," said to be used as a salutation in parting. The phrase seems to have turned up simultaneously in America, Britain, and perhaps Canada, originally among lower classes. First attested use is in title and text of the last poem in Whitman's "Leaves of Grass" in the 1860 edition.
An unknown sphere, more real than I dream'd, more direct, darts awakening rays about me — So long!
Remember my words — I may again return,
I love you — I depart from materials;
I am as one disembodied, triumphant, dead.
Whitman's friend and fan William Sloane Kennedy wrote in 1923:
The salutation of parting — 'So long!' — was, I believe, until recent years, unintelligible to the majority of persons in America, especially in the interior, and to members of the middle and professional classes. I had never heard of it until I read it in Leaves of Grass, but since then have quite often heard it used by the laboring class and other classes in New England cities. Walt wrote to me, defining 'so long' thus: "A salutation of departure, greatly used among sailors, sports, & prostitutes — the sense of it is 'Till we meet again,' — conveying an inference that somehow they will doubtless so meet, sooner or later." ... It is evidently about equivalent to our 'See you later.' The phrase is reported as used by farm laborers near Banff, Scotland. In Canada it is frequently heard; 'and its use is not entirely confined to the vulgar.' It is in common use among the working classes of Liverpool and among sailors at Newcastle-upon-Tyne, and in Dorsetshire. ... The London Globe suggests that the expression is derived from the Norwegian 'Saa laenge,' a common form of 'farewell,' au revoir. If so, the phrase was picked up from the Norwegians in America, where 'So long' first was heard. The expression is now (1923) often used by the literary and artistic classes.
a Middle English merger of Old English line "cable, rope; series, row, row of letters; rule, direction," and Old French ligne "guideline, cord, string; lineage, descent" (12c.), both from Latin linea "linen thread, string, plumb-line," also "a mark, bound, limit, goal; line of descent," short for linea restis "linen cord," and similar phrases, from fem. of lineus (adj.) "of linen," from linum "linen" (see linen).
The earliest sense in Middle English was "cord used by builders for taking measurements;" extended late 14c. to "a thread-like mark" (from sense "cord used by builders for making things level," mid-14c.), also "track, course, direction." Meaning "limit, boundary" (of a county, etc.) is from 1590s. The mathematical sense of "length without breadth" is from 1550s. From 1530s as "a crease of the face or palm of the hand." From 1580s as "the equator."
Sense of "things or people arranged in a straight line" is from 1550s. Now considered American English, where British English uses queue (n.), but the sense appears earliest in English writers. Sense of "chronologically continuous series of persons" (a line of kings, etc.) is from late 14c.
Meaning "one's occupation, branch of business" is from 1630s, according to OED probably from misunderstood KJV translation of II Corinthians x.16, "And not to boast in another mans line of things made ready to our hand," where line translates Greek kanon which probably meant "boundary, limit;" the phrase "in another man's line" being parenthetical.
Commercial meaning "class of goods in stock" is from 1930, so called from being goods received by the merchant on a line in the specific sense "order given to an agent" for particular goods (1834). Insurance underwriting sense is from 1899. Line of credit is from 1958.
Meaning "series of public conveyances" (coaches, later ships) is from 1786; meaning "continuous part of a railroad" is from 1825. Meaning "telegraph wire between stations" is from 1847 (later "telephone wire"). Meaning "cord bearing hooks used in fishing" is from c. 1300. Meaning "policy or set of policies of a political faction" is 1892, American English, from notion of a procession of followers; this is the sense in the political party line, and, deteriorated, it is the slang line that means "glib and plausible talk meant to deceive."
In British army, the Line (1802) is the regular, numbered troops, as distinguished from guards, auxiliaries, militia, etc. In the Navy (1704) it refers to the battle line (the sense in ship of the line, which is attested from 1706).
Dutch lijn, Old High German lina, German Leine, Old Norse lina "a cord, rope," are likewise from Latin. Spanish and Italian have the word in the learned form linea. In continental measurements, a subdivision of an inch (one-tenth or one-twelfth in England), attested in English from 1660s but never common. Also see lines.
To get a line on "acquire information about" is from 1903. To lay it on the line is from 1929 as "to pay money;" by 1954 as "speak plainly." End of the line "as far as one can go" is from 1948. One's line of work, meaning "pursuit, interest" is from 1957, earlier line of country (1861). Line-drawing is from 1891. A line-storm (1850) is a type supposed to happen in the 10 days or two weeks around the times the sun crosses the equator.
"a featherless plantigrade biped mammal of the genus Homo" [Century Dictionary], Old English man, mann "human being, person (male or female); brave man, hero;" also "servant, vassal, adult male considered as under the control of another person," from Proto-Germanic *mann- (source also of Old Saxon, Swedish, Dutch, Old High German man, Old Frisian mon, German Mann, Old Norse maðr, Danish mand, Gothic manna "man"), from PIE root *man- (1) "man." For the plural, see men.
Sometimes connected to root *men- (1) "to think," which would make the ground sense of man "one who has intelligence," but not all linguists accept this. Liberman, for instance, writes, "Most probably man 'human being' is a secularized divine name" from Mannus [Tacitus, "Germania," chap. 2], "believed to be the progenitor of the human race."
Specific sense of "adult male of the human race" (distinguished from a woman or boy) is by late Old English (c. 1000); Old English used wer and wif to distinguish the sexes, but wer began to disappear late 13c. and was replaced by man. Universal sense of the word remains in mankind and manslaughter. Similarly, Latin had homo "human being" and vir "adult male human being," but they merged in Vulgar Latin, with homo extended to both senses. A like evolution took place in Slavic languages, and in some of them the word has narrowed to mean "husband." PIE had two other "man" roots: *uiHro "freeman" (source of Sanskrit vira-, Lithuanian vyras, Latin vir, Old Irish fer, Gothic wair; see *wi-ro-) and *hner "man," a title more of honor than *uiHro (source of Sanskrit nar-, Armenian ayr, Welsh ner, Greek anēr; see *ner- (2)).
Man also was in Old English as an indefinite pronoun, "one, people, they." It was used generically for "the human race, mankind" by c. 1200. As a word of familiar address, originally often implying impatience, c.1400; hence probably its use as an interjection of surprise or emphasis, since Middle English but especially popular from early 20c.
As "a woman's lover," by mid-14c. As "adult male possessing manly qualities in an eminent degree," from 14c. Man's man, one whose qualities are appreciated by other men, is by 1873. Colloquial use of the Man for "the boss" is by 1918. To be man or mouse "be brave or be timid" is from 1540s. Meaning "piece with which a game (especially chess) is played" is from c. 1400.
Man-about-town "man of the leisure class who frequents clubs, theaters, and other social resorts" is from 1734. Man of the world is from mid-14c. as "secular man, layman;" by early 15c. as "man experienced in the ways of the world, one able to take things in stride." To do something as one man "unanimously" is from late 14c.
So I am as he that seythe, 'Come hyddr John, my man.' 
MANTRAP, a woman's commodity. [Grose, "Dictionary of the Vulgar Tongue," London, 1785]
At the kinges court, my brother, Ech man for himself. [Chaucer, "Knight's Tale," c. 1386]