late 14c., ynneside "interior part (of the body)," compound of in (prep.) + side (n.). General sense "inner side or part (of anything)" is from c. 1500.

The adjective sense "being on the inside" is from 1610s, from the noun. It began to be used in slang c. 1900 in reference to the supposed real facts or situation that only an insider would know. Inside man is from 1911 (originally in reference to workers used by management to sniff out union activity); inside job "robbery, espionage, etc., committed by or with the help of a resident or servant of a place" is attested by 1887, American English (also, late 19c., early 20c., "indoors work").

The figurative inside track "advantage" (1854) however is a metaphor from horse racing (1830); inside lanes are shorter than the outer ones on a curved track. Adverbial use in American English inside of (in reference to time) is from 1839.

late 15c., "floating platform of timber lashed or fastened together," from earlier meaning "rafter, beam" (c. 1300), from a Scandinavian source such as Old Norse raptr "log" (Old Norse -pt- pronounced as -ft-), Old Danish raft, related to Middle Low German rafter, rachter "rafter" (see rafter (n.1)).

In North America, rafts are constructed of immense size, and comprise timber, boards, staves, etc. They are floated down from the interior to the tide-waters, being propelled by the force of the current, assisted by large oars and sails, to their place of destination. The men employed on these rafts construct rude huts upon them, in which they often dwell for several weeks before arriving at the places where they are taken to pieces for shipping to foreign parts. [Bartlett, "Dictionary of Americanisms," 2nd ed., 1859]

words on the Great Seal of the United States of America, condensed by Charles Thompson, designer of the seal in its final form, from Latin Juppiter omnipotes, audacibus annue coeptis "All-powerful Jupiter favor (my) daring undertakings," line 625 of book IX of Virgil's "Aeneid." The words also appear in Virgil's "Georgics," book I, line 40: Da facilem cursam, atque audacibus annue coeptis "Give (me) an easy course, and favor (my) daring undertakings."

Thompson changed the imperative annue to annuit, the third person singular form of the same verb in either the present tense or the perfect tense. The motto also lacks a subject. The motto is often translated as "He (God) is favorable to our undertakings," but this is not the only possible translation.

Thomson wrote: "The pyramid signifies Strength and Duration: The Eye over it & Motto allude to the many signal interpositions of providence in favour of the American cause." The original design (by William Barton) showed the pyramid and the motto Deo Favente Perennis "God favoring through the years."

The Latin elements are the perfective of annuere "indicate approval, agree to, grant," literally "nod to (as a sign)" (from assimilated form of ad "to;" see ad-, + nuere "to nod;" see numinous) + perfect passive of coeptus, past participle of coepere "to begin, commence."

late 14c., "suffering, anguish; act or fact of pressing on the mind or heart," from Old French presseure "oppression; torture; anguish; press" (for wine or cheeses), "instrument of torture" (12c.) and directly from Latin pressura "action of pressing," from pressus, past participle of premere "to press, hold fast, cover, crowd, compress" (from PIE root *per- (4) "to strike").

The literal meaning "act or fact of pressing" in a physical sense is attested in English from early 15c. The meaning "moral or mental coercing force, exertion of authority or influence" is from 1620s; the meaning "urgency, demand on one's time or energies" is from 1812. Scientific sense in physics, "force per unit area exerted over a surface and toward the interior" is from 1650s.

Pressure cooker "airtight vessel in which food is cooked in steam under pressure" is attested from 1915; figurative sense is from 1958. Pressure point of the skin is attested from 1876. Pressure-treated, of woods impregnated with a preservative fluid under pressure, is from 1911.

mid-14c., celynge, "act of paneling a room," noun formed (with -ing) from Middle English verb ceil "put a cover or ceiling over," later "cover (walls) with wainscoting, panels, etc." (early 15c.); from Old French celer "conceal," also "cover with paneling" (12c.), from Latin celare "to hide" (from PIE root *kel- (1) "to cover, conceal, save"). Probably influenced by Latin caelum "heaven, sky" (see celestial).

Extended to the paneling itself from late 14c., then to lath-and-plaster work. The meaning "interior overhead surface of a room" is attested by 1530s; by late 19c. the meaning "wainscoting" was only in provincial English. Figurative sense of "upper limit" is from 1934.

Colloquial figurative phrase hit the ceiling "lose one's temper, get explosively angry" is attested by 1908; earlier it meant "to fail" (by 1900, originally U.S. college slang). Glass ceiling in the figurative sense of "invisible barrier that prevents women from advancing" in management, etc., is attested from 1988.

Middle English roum, from Old English rum "space, extent; sufficient space, fit occasion (to do something)," from Proto-Germanic *ruman (source also of Old Norse, Old Saxon, Old High German, Gothic rum, German Raum "space," Dutch ruim "hold of a ship, nave"), nouns formed from Germanic adjective *ruma- "roomy, spacious," from PIE root *reue- (1) "to open; space" (source also of Avestan ravah- "space," Latin rus "open country," Old Irish roi, roe "plain field," Old Church Slavonic ravinu "level," Russian ravnina "a plain").

Old English also had a frequent adjective rum "roomy, wide, long, spacious," also an adverb, rumlice "bigly, corpulently" (Middle English roumli).

The meaning "chamber, cabin" is recorded by early 14c. as a nautical term; applied by mid-15c. to interior division of a building separated by walls or partitions; the Old English word for this was cofa, ancestor of cove. The sense of "persons assembled in a room" is by 1712.

Make room "open a passage, make way" is from mid-15c.  Room-service is attested from 1913; room-temperature, comfortable for the occupants of a room, is so called from 1879. Roomth "sufficient space" (1530s, with -th (2)) now is obsolete.

Old English weall, Anglian wall "rampart, dike, earthwork" (natural as well as man-made), "dam, cliff, rocky shore," also "defensive fortification around a city, side of a building," an Anglo-Frisian and Saxon borrowing (Old Saxon, Old Frisian, Middle Low German, Middle Dutch wal) from Latin vallum "wall, rampart, row or line of stakes," apparently a collective form of vallus "stake," from PIE *walso- "a post." Swedish vall, Danish val are from Low German.

Meaning "interior partition of a structure" is mid-13c. In this case, English uses one word where many languages have two, such as German Mauer "outer wall of a town, fortress, etc.," used also in reference to the former Berlin Wall, and wand "partition wall within a building" (compare the distinction, not always rigorously kept, in Italian muro/parete, Irish mur/fraig, Lithuanian mūras/siena, etc.). The Latin word for "defensive wall" was murus (see mural).

Anatomical use from late 14c. To give (someone) the wall "allow him or her to walk on the (cleaner) wall side of the pavement" is from 1530s. To turn (one's) face to the wall "prepare to die" is from 1570s. Phrase up the wall "angry, crazy" is from 1951; off the wall "unorthodox, unconventional" is recorded from 1966, American English student slang. To go over the wall "escape" (originally from prison) is from 1933. Wall-to-wall (adj.) recorded 1939, of shelving, etc.; metaphoric use (usually disparaging) is from 1967.

mid-13c., musike, "a pleasing succession of sounds or combinations of sounds; the science of combining sounds in rhythmic, melodic, and (later) harmonic order," from Old French musique (12c.) and directly from Latin musica "the art of music," also including poetry (also source of Spanish musica, Italian musica, Old High German mosica, German Musik, Dutch muziek, Danish musik), from Greek mousikē (technē) "(art) of the Muses," from fem. of mousikos "pertaining to the Muses; musical; educated," from Mousa "Muse" (see muse (n.)).

The modern spelling is from 1630s. In classical Greece, any art in which the Muses presided, but especially music and lyric poetry.

Music is the sound of the universal laws promulgated. [Thoreau]

The use of letters to denote music pitch probably is at least as old as ancient Greece, as their numbering system was ill-suited to the job. Natural scales begin at C (not A) because in ancient times the minor mode was more often used than the major one, and the natural minor scale begins at A.

Meaning "the written or printed score of a composition" is from 1650s.

Music box is from 1773, originally "barrel organ," by 1845 in reference to the wind-up mechanical device; music hall is by 1842 as "interior space used for musical performances," especially "public hall licensed for musical entertainment" (1857). To face the music "accept the consequences" is from 1850; the exact image is uncertain, one theory ties it to stage performers, another to cavalry horses having to be taught to stay calm while the regimental band plays. To make (beautiful) music with someone "have sexual intercourse" is from 1967.

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.