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 or influenced by 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, with sense as in the German phrase. Etymology sources seem to lean toward the German origin. The adverbial so long "for such a long time" is from late Old English (swa lange); see so.

Earlier guesses that it was a sailors' corruption of a South Pacific form of Arabic salaam are not now 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. The 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 expression is now (1923) often used by the literary and artistic classes.

1726, "morbid longing to return to one's home or native country, severe homesickness considered as a disease," Modern Latin, coined 1688 in a dissertation on the topic at the University of Basel by scholar Johannes Hofer (1669-1752) as a rendering of German heimweh "homesickness" (for which see home + woe).

From Greek algos "pain, grief, distress" (see -algia) + nostos "homecoming," from neomai "to reach some place, escape, return, get home," from PIE *nes- "to return safely home" (cognate with Old Norse nest "food for a journey," Sanskrit nasate "approaches, joins," German genesen "to recover," Gothic ganisan "to heal," Old English genesen "to recover"). French nostalgie is in French army medical manuals by 1754.

Originally in reference to the Swiss and said to be peculiar to them and often fatal, whether by its own action or in combination with wounds or disease.

[Dr. Scheuzer] had said that the air enclosed in the bodies of his countrymen, being in Æquilibrium with a rare and light air that surrounds them, was overloaded in lower countries with an air more dense and heavier, which compressing and obstructing the capillary vessels, makes the circulation slow and difficult, and occasions many sad symptoms. [Account of the publication of "Areographia Helvetiæ" in New Memoirs of Literature, London, March 1726] 

By 1830s the word was used of any intense homesickness: that of sailors, convicts, African slaves. "The bagpipes produced the same effects sometimes in the Scotch regiments while serving abroad" [Penny Magazine," Nov. 14, 1840]. It is listed among the "endemic diseases" in the "Cyclopaedia of Practical Medicine" [London, 1833, edited by three M.D.s], which defines it as "The concourse of depressing symptoms which sometimes arise in persons who are absent from their native country, when they are seized with a longing desire of returning to their home and friends and the scenes their youth ...."

It was a military medical diagnosis principally, and was considered a serious medical problem by the North in the American Civil War:

In the first two years of the war, there were reported 2588 cases of nostalgia, and 13 deaths from this cause. These numbers scarcely express the real extent to which nostalgia influenced the sickness and mortality of the army. To the depressing influence of home-sickness must be attributed the fatal result in many cases which might otherwise have terminated favorably. ["Sanitary Memoirs of the War," U.S. Sanitary Commission, N.Y.: 1867]

Transferred sense (the main modern one) of "wistful yearning for the past" is recorded by 1920, perhaps from such use of nostalgie in French literature. The longing for a distant place also necessarily involves a separation in time.

"monetary unit or standard of value in the U.S. and Canada," 1550s, daler, originally in English the name of a large, silver coin of varying value in the German states, from Low German daler, from German taler (1530s, later thaler), abbreviation of Joachimstaler, literally "(gulden) of Joachimstal," coin minted 1519 from silver from mine opened 1516 near Sankt Joachimsthal, town in Erzgebirge Mountains in northwest Bohemia. German Tal is cognate with English dale. The spelling had been modified to dollar by 1600.

The thaler was from 17c. the more-or-less standardized coin of northern Germany (as opposed to the southern gulden). It also served as a currency unit in Denmark and Sweden (and later was a unit of the German monetary union of 1857-73 equal to three marks).

English colonists in America used the word dollar from 1580s in reference to Spanish peso or "piece of eight," also a large silver coin of about the same fineness as the thaler. Due to extensive trade with the Spanish Indies and the proximity of Spanish colonies along the Gulf Coast, the Spanish dollar probably was the coin most familiar in the American colonies and the closest thing to a standard in all of them.

When the Revolution came, it had the added advantage of not being British. It was used in the government's records of public debt and expenditures, and the Continental Congress in 1786 adopted dollar as a unit when it set up the modern U.S. currency system, which was based on the suggestion of Gouverneur Morris (1782) as modified by Thomas Jefferson. None were circulated until 1794.

When William M. Evarts was Secretary of State he accompanied Lord Coleridge on an excursion to Mount Vernon. Coleridge remarked that he had heard it said that Washington, standing on the lawn, could throw a dollar clear across the Potomac. Mr. Evarts explained that a dollar would go further in those days than now. [Walsh]

Phrase dollars to doughnuts "an assured thing, a certainty" (such that one would bet a dollar against a doughnut on it) is attested by 1884; dollar diplomacy "financial imperialism, foreign policy based on financial and commercial interests" is from 1910.

The dollar sign ($) is said to derive from the image of the Pillars of Hercules, stamped with a scroll, on the Spanish piece of eight. However, according to the Bureau of Engraving and Printing of the U.S. Department of the Treasury:

[T]he most widely accepted explanation is that the symbol is the result of evolution, independently in different places, of the Mexican or Spanish "P's" for pesos, or piastres, or pieces of eight. The theory, derived from a study of old manuscripts, is that the "S" gradually came to be written over the "P," developing a close equivalent of the "$" mark. It was widely used before the adoption of the United States dollar in 1785.

[stone, mass of mineral matter], Middle English rokke, roche "stone as a substance; large rocky formation, rocky height or outcrop, crag," from Old English rocc (as in stanrocc "stone rock or obelisk") and directly from Old North French roque, variant of Old French roche, which is cognate with Medieval Latin rocca (8c.), from Vulgar Latin *rocca, a word of uncertain origin. According to Klein and Century Dictionary, sometimes said to be from Celtic (compare Breton roch). Diez suggests Vulgar Latin *rupica, from Latin rupes "rocks."

In Middle English it seems to have been used principally for large rock formations but occasionally of individual boulders. The extended sense of "a stone of any size" is by 1793, American English colloquial, and long was considered incorrect.

It is an error to use rock for a stone so small that a man can handle it : only a fabulous person or a demi-god can lift a rock. [Century Dictionary]

The meaning "precious stone," especially a diamond, is by 1908, U.S. slang; the sense of "crystallized cocaine" is attested from 1973 in West Coast slang. Also used attributively in names of animals that frequent rocky habitats, as in rockfish, rock badger, rock lobster (the last attested by 1843).

Rock is used figuratively for "a sure foundation, something which gives one protection and security" (especially with reference to Christ), from the 1520s (Tyndale); but it also has been used since the 1520s as "cause or source of peril or destruction," an image from shipwrecks.

Between a rock and a hard place "beset by difficulties with no good alternatives" is attested by 1914 in U.S. Southwest:

to be between a rock and a hard place, vb. ph. To be bankrupt. Common in Arizona in recent panics; sporadic in California. [Dialect Notes, vol. v, part iv, 1921]

As an example of fine distinctions, a party of men were discussing the present situation of the German army, this week. One remarked that the Germans were between the devil and the deep sea; while another corrected him by saying that the Germans were between the upper and nether mill stone. The third man whose name is Pilgreen, and who works in the treasurer's office, simply remarked that the Germans were between a rock and a hard place. [local item in the Pouteau (Oklahoma) Weekly Sun,  Oct. 1, 1914]

The rock-scissors-paper game is attested by that name by 1976 (as paper stone and scissors by 1941). Sources agree it is based on Japanese Jan Ken Po or Jan Ken Pon (or Janken for short); the Japanese game is described in English publications by 1879.

early 15c., "devoted to or relating to home life;" 1560s as "living with others," from French social (14c.) and directly from Latin socialis "of companionship, of allies; united, living with others; of marriage, conjugal," from socius "companion, ally," probably originally "follower," from PIE *sokw-yo-, suffixed form of root *sekw- (1) "to follow." Compare Old English secg, Old Norse seggr "companion," which seem to have been formed in Germanic on the same notion. Related: Socially.

It is attested by 1660s as "marked by mutual intercourse, enjoyed in the company of others," especially those of similar inclinations. Of a club, etc., "comprised of persons coming together for friendly intercourse," by 1792.

The broader sense of "living or liking to live with others; companionable, disposed to live in companies or communities" is from 1722. Social drinking "consumption of alcohol in a social context" is attested by 1807; social butterfly (1867) is a figurative reference to "flitting" from one social event to another. Social network is attested by 1971; social networking by 1984; social media by 2008.

The meaning "of or pertaining to society as a natural human state," and to its ranks and conditions, is attested by 1695 in Locke. Social contract (1763), the mutual agreement supposed to form the basis of human society, is from translations of Rousseau.

Hence also social science (1785). Social studies as an inclusive term for history, geography, economics, etc., is attested from 1916. Social security "system of state support for needy citizens" is attested from 1907 (the Social Security Act was passed by U.S. Congress in 1935).

And in reference to problems rooted in social conditions, social work (1890); social worker (1886). In late 19c. newspapers, social evil is "prostitution." Social justice is attested by 1718. Specifically of activities, especially by governments, meant to improve the condition of society overall, by 1964.

Social Darwinism "application of the theory of evolution to social situations" is attested from 1887. Social engineering, "application of sociology theory to specific problems" is attested by 1899.

The sense of "of or concerned with fashionable society and the leisured class" is from 1873. Hence social register "published list of those who are socially prominent," attested by 1889, American English; social climber, "one who seeks to advance socially" (1893).

Social distance was originally in a psychological sense in reference to societies (1924); it was used in reference to "physical distance acceptable in social situations" by 1955.

A social war (1660s) is one between allies, especially (with capitals) in reference to the Roman war 90-88 B.C.E. in which the Roman allies (socii) fought for citizenship rights.

I must introduce a parenthetical protest against the abuse of the current term 'social justice'. From meaning 'justice in relations between groups or classes' it may slip into meaning a particular assumption as to what these relations should be; and a course of action might be supported because it represented the aim of 'social justice', which from the point of view of 'justice' was not just. The term 'social justice' is in danger of losing its rational content—which would be replaced by a powerful emotional charge. I believe that I have used the term myself: it should never be employed unless the user is prepared to define clearly what social justice means to him, and why he thinks it just. [T.S. Eliot, footnote in "Notes Towards the Definition of Culture," 1948]

late 14c. (perhaps mid-13c. in Anglo-French), grave, gravei, gravi, greve, gravey, gravee, grovi, grauvey, with u/v variation typical of medieval spelling. From Old French gravé, graué, "seasoned broth or sauce," ultimately from Persian zirbaja, said by H.F. Amedroz to mean “concoction in a pot.” The unattested intermediate term should have been something like *girveie (see evolution of ginger for comparison.) 

The dish became popular in Europe in the 14th century, probably introduced through the Emirate of Granada in what is now Spain.

Recipe for Zîrbâja […] Take a young, cleaned hen and put it in a pot with a little salt, pepper, coriander, cinnamon, saffron and sufficient of vinegar and fresh oil, and when the meat is cooked, take peeled, crushed almonds and good white sugar, four ûqiyas of each; dissolve them in rosewater, pour in the pot and let it boil; then leave it on the embers until the fat rises. It is the most nutritious of dishes and good for all temperaments; this dish is made with hens or pigeons or doves, or with the meat of a young lamb. [An Anonymous Andalusian Cookbook of the 13th Century, translated by Charles Perry.]

Conyngys in graueye. Take Conyngys, and make hem clene, and hakke hem in gobettys, and sethe hem, other larde hem and Rost hem; and thanne hakke hem, and take Almaundys, and grynde hem, and temper hem vppe with gode Freysshe brothe of Flesshe, and coloure it wyth Safroun, and do ther-to a porcyon of flowre of Rys, and do ther-to then pouder Gyngere, Galyngale, Canel, Sugre, Clowys, Maces, and boyle it onys and sethe it; then take the Conyngys, and putte ther-on, and dresse it and serue it forth. [Harleian MS 279, date ca. 1420]

It is usually said that gravé is a non-word created as a mistranscription of grané, a similar mixture with which it is indeed conflated in French manuscripts. Grané is usually supposed to be from Medieval Latin granatum “corned, grained” but this is unattested in the context of this sauce. It is as likely in this case to be from "Granada" (see Granada.) 

There may have been a second word, combined through folk-etymology, that led to the secondary sense of "juice of cooked meat." Perhaps Old French engravee "carved, sliced" or Old English greofa, an oil-pan (related to greaves, 1610s, "fibrous matter cooked out of animal fat.")

In Middle English the word grave is glossed against Latin garus, "a type of fish used for making sauce" and promulada, probably from promulsis, an old appetizer of eggs and fish. The sense of broths or drippings appears to originally be of fishes, then soon extended to meat drippings or gelatin, which sense grows dominant in English from mid-15c, though still used most typically of fish or other seafood till 16c.

As "a sauce made with meat drippings," 1670s, originally sauce gravy or gravy sauce. Applied to vegetarian mixtures by 1875. The meaning "tomato sauce" (chiefly Italian-American) is by 1978, evidently from certain Italian dialects differentiating tomato puree (salsa, "sauce") from the cooked tomato sauce (sugo, translated "gravy" in many 19c. and 20c. Italian-English dictionaries, or ragu, etc.)

The meaning "money easily acquired" is attested by 1910; gravy train (by 1899) as something lucrative or productive is said to have been originally railroad slang for a short haul that paid well. Gravy-boat "small, deep dish for holding gravy or sauce" is from 1827.