Online Etymology Dictionary

schnook (n.): 1948, probably from Yiddish shnuk "elephant's trunk," or altered from schmuck (q.v.), or perhaps from German schnucke "a small sheep," used in U.S. Yiddish for "a customer easily persuaded, a sucker."
schnorrer (n.): 1892, from Yiddish, "beggar," from German slang schnurrer, from schnurren "to go begging" (slang), perhaps ultimately imitative of the sound of pleading or whining (e.g. sneer, snorkel, snarl).
schnozz (n.): "nose," 1942, from Yiddish shnoitsl, from German Schnauze "snout" (see schnauzer).
scholar (n.): Old English scolere "student," from Medieval Latin scholaris, from Late Latin scholaris "of a school," from Latin schola (see school (n.1)). The Medieval Latin word widely borrowed, e.g. Old French escoler, French écolier, Old High German scuolari, German Schüler.
scholarly (adj.): 1630s, from scholar + -ly (1).
scholarship (n.): 1530s, from scholar + -ship.
scholastic (adj.): 1590s, "of or pertaining to Scholastic theologians" (Churchmen in the Middle Ages whose theology and philosophy was based on Church Fathers and Aristotle), from Middle French scholastique, from Latin scholasticus "learned," from Greek skholastikos "studious, learned" (see school (n.1)). Meaning "pertaining to schools or to school education" is from 1640s.
Scholasticism (n.): mid-18c., from scholastic + -ism.
scholiast (n.): "one who writes explanatory notes upon a classical writer," 1580s, from Late Latin scholiasta, from Late Greek skholiastes, from skholiazein, from skholion "explanatory note or comment," from skhole (see school (n.1)).
school (n.1): "place of instruction," Old English scol, from Latin schola, from Greek skhole "school, lecture, discussion," also "leisure, spare time," originally "a holding back, a keeping clear," from skhein "to get," from PIE root *segh- "to hold, hold in one's power, to have" (see scheme (n.)) + -ole by analogy with bole "a throw," stole "outfit," etc.

The original notion is "leisure," which passed to "otiose discussion," then "place for such." The Latin word was widely borrowed, cf. Old French escole, French école, Spanish escuela, Italian scuola, Old High German scuola, German Schule, Swedish skola, Gaelic sgiol, Welsh ysgol, Russian shkola. Replaced Old English larhus "lore house."

Meaning "students attending a school" is attested from c.1300; sense of "school building" is first recorded 1590s. Sense of "people united by a general similarity of principles and methods" is from 1610s; hence school of thought (1864). School of hard knocks "rough experience in life" is recorded from 1912 (in George Ade); to tell tales out of school "betray damaging secrets" is from 1540s.
school (n.2): "group of fish," c.1400, from Middle Dutch schole "group of fish or other animals," cognate with Old English scolu "band, troop, school of fish," from West Germanic *skulo- (see shoal (n.2)).
school (v.): 1570s, from school (n.1). Related: Schooled; schooling.
schoolgirl (n.): 1777, from school (n.1) + girl.
schoolmarm (n.): also school-marm, "female school teacher," 1834, American English colloquial, in countrified humor writing of "Major Jack Downing" of Maine (Seba Smith); variant of school-ma'am (1828), American English, from school (n.1) + ma'am.
The moment we encounter the added r's of purp or dorg in our reading we know that we have to do with humor, and so with school-marm. The added consonants are supposed to be spoken, if the words are uttered, but, as a matter of fact, they are less often uttered than seen. The words are, indeed, largely visual forms; the humor is chiefly for the eye. [Louise Pound, "The Humorous 'R,'" "American Mercury," October 1924]
She goes on to note that in British humorous writing, -ar "popularly indicates the sound of the vowel in father" and formations like larf (for laugh) "are to be read with the broad vowel but no uttered r." She also quotes Henry James on the characteristic prominence of the medial -r- sound, which tends to be dropped in England and New England, in the speech of the U.S. Midwest, "under some strange impulse received toward consonantal recovery of balance, making it present even in words from which it is absent, bringing it in everywhere as with the small vulgar effect of a sort of morose grinding of the back teeth."

Used figuratively from 1887 in reference to patronizing and priggish instruction.
schooner (n.): 1716, perhaps from a New England verb related to Scottish scon "to send over water, to skip stones." Skeat relates this dialectal verb to shunt. Spelling probably influenced by Dutch, but Dutch schoener is a loan-word from English, as are German Schoner, French schooner, Swedish skonert. Said to have originated in Gloucester, Mass., shipyard.
The rig characteristic of a schooner has been defined as consisting essentially of two gaff sails, the after sail not being smaller than the fore, and a head sail set on a bowsprit. [OED]
Meaning "tall beer glass" is from 1879, of unknown origin.
schottische (n.): round dance resembling a polka, 1849, from German Schottische, from schottische "Scottish," from Schotte "a native of Scotland," from Old High German Scotto, from Late Latin Scottus (see Scot). The pronunciation is French.
schuhplattler (n.): "lively Alpine folk dance," 1874, from German, from schuh "shoe" (see shoe) + south German dialectal plattler, from platteln "to dance."
Schutzstaffel: "internal security force of Nazi Germany," 1930, German, literally "defense squadron." Better known by its initials, S.S.
schvartze (n.): "black person" (somewhat derogatory), 1961, from Yiddish, from schvarts "black" (see swarthy). Perhaps originally a code word to refer to black servants when they were within earshot, as German cognate Schwarze apparently was in the mid-19c.:
In Baltimore in the 80s of the last century, the German-speaking householders, when they had occasion to speak of Negro servants in their presence, called them die Blaue (blues). In the 70s die Schwartze (blacks) had been used, but it was believed that the Negroes had fathomed it. [H.L. Mencken, "The American Language," Supplement I, 1945]
schwa (n.): 1895, from German Schwa, ultimately from Hebrew shewa "a neutral vowel quality," literally "emptiness."
Schwenkfeldian: 1560s, from Casper Schwenkfeld (1490-1561), Silesian Protestant mystic who founded the sect. Schwenkfelder is attested from 1882.
sciamachy (n.): "fighting with shadows, shadow-boxing" 1620s, from Greek skiamakhia "shadow-fighting, a sham fight" but perhaps literally "fighting in the shade" (i.e., in school), from skia "shade, shadow" (see shine) + makhe "battle."
sciatic (adj.): 1540s, from French sciatique, from Medieval Latin sciaticus (see sciatica).
sciatica (n.): late 14c., from Medieval Latin sciatica, in sciatica passio "sciatic disease," from fem. of sciaticus "sciatic," from Latin ischiadicus "of pain in the hip," from Greek iskhiadikos, from iskhias (genitive iskhiados) "pain in the hips," from iskhion "hip joint."
science (n.): c.1300, "knowledge (of something) acquired by study," also "a particular branch of knowledge," from Old French science, from Latin scientia "knowledge," from sciens (genitive scientis), present participle of scire "to know," probably originally "to separate one thing from another, to distinguish," related to scindere "to cut, divide," from PIE root *skei- (cf. Greek skhizein "to split, rend, cleave," Gothic skaidan, Old English sceadan "to divide, separate;" see shed (v.)).
Science, since people must do it, is a socially embedded activity. It progresses by hunch, vision, and intuition. Much of its change through time does not record a closer approach to absolute truth, but the alteration of cultural contexts that influence it so strongly. Facts are not pure and unsullied bits of information; culture also influences what we see and how we see it. Theories, moreover, are not inexorable inductions from facts. The most creative theories are often imaginative visions imposed upon facts; the source of imagination is also strongly cultural. [Stephen Jay Gould, introduction to "The Mismeasure of Man," 1981]
Modern sense of "non-arts studies" is attested from 1670s. The distinction is commonly understood as between theoretical truth (Greek episteme) and methods for effecting practical results (tekhne), but science sometimes is used for practical applications and art for applications of skill. Main modern (restricted) sense of "body of regular or methodical observations or propositions ... concerning any subject or speculation" is attested from 1725; in 17c.-18c. this concept commonly was called philosophy. To blind (someone) with science "confuse by the use of big words or complex explanations" is attested from 1937, originally noted as a phrase from Australia and New Zealand.
science fiction (n.): 1929 (first attested in "Science Wonder Stories" magazine), though there is an isolated use from 1851; abbreviated form sci-fi is from 1955.
scienter: Latin, literally "knowingly," from sciens, present participle of scire "to know" (see science) + adv. suffix -ter.
scientific (adj.): 1580s, from Middle French scientifique, from Medieval Latin scientificus "pertaining to science," from Latin scientia "knowledge" (see science) + -ficus "making" + facere "to make" (see factitious). Originally used to translate Greek epistemonikos "making knowledge" in Aristotle's "Ethics." First record of scientific revolution is from 1803; scientific method is from 1854; scientific notation is from 1961. Related: Scientifical.
scientist (n.): 1834, coined from Latin scientia (see science) by the Rev. William Whewell (1794-1866), English polymath, by analogy with artist.
Scientology (n.): 1951, system of beliefs founded by L. Ron Hubbard. According to www.scientology.org:
The word Scientology, conceived by L. Ron Hubbard, comes from the Latin scio which means "knowing, in the fullest meaning of the word" and the Greek word logos which means "study of." It means knowing how to know. Scientology is further defined as "the study and handling of the spirit in relationship to itself, universes and other life."
There was a German scientologie (A. Nordenholz, 1937).
scilicet: late 14c., Latin, contraction of scire licit "it is permitted to know."
Scilly: isles off Cornwall, of unknown origin. Pliny has Silumnus, Silimnis. Perhaps connected with the Roman god Sulis (cf. Aquae sulis "Bath"). The -y might be Old Norse ey "island" The -c- added 16c.-17c. "[A]bout the only certain thing that can be said is that the c of the modern spelling is not original but was added for distinction from ModE silly as this word developed in meaning from 'happy, blissful' to 'foolish.'" [Victor Watts, "Cambridge Dictionary of English Place-Names," 2004].
scimitar (n.): 1540s, from Middle French cimeterre (15c.) or Italian scimitarra, of uncertain origin. Turkish would be the expected source, but no such word has been found there. Perhaps from Persian shimshir (pronounced "shamsher," cf. Greek sampsera "a barbarian sword," from this source), but OED finds this "unsatisfactory as to form." Many early variations; the modern spelling is from influence of the Italian form of the word.
scintilla (n.): 1690s, from figurative use of Latin scintilla "particle of fire, spark, glittering speck, atom," probably from PIE *ski-nto-, from root *skai- "to shine, to gleam" (cf. Gothic skeinan, Old English scinan "to shine;" see shine (v.)).
scintillate (v.): 1620s, from Latin scintillatus, past participle of scintillare "to sparkle," from scintilla "spark" (see scintilla). Related: Scintillated; scintillating.
scintillation (n.): 1620s, from Latin scintilationem (nominative scintillatio), noun of action from past participle stem of scintillare (see scintillate).
sciolism (n.): 1816; see sciolist + -ism.
sciolist (n.): 1610s, "smatterer, pretender to knowledge," from Late Latin sciolus "one who knows a little," diminutive of scius "knowing," from scire "to know" (see science) + -ist.
sciomancy (n.): "divination by communication with shades of the dead," 1620s, from Modern Latin sciomantia, from scio-, Latinized comb. form of Greek skia "shade, shadow" (see shine (v.)) + Latinized form of Greek manteia (see -mancy).
scion (n.): c.1300, "a shoot or twig," from Old French sion, cion (Modern French scion, Picard chion), of uncertain origin. Perhaps from Frankish *kid-, from Proto-Germanic *kidon-, from PIE *geie- "to sprout, split, open" (see chink (n.1)). Figurative use is attested from 1580s; meaning "an heir, a descendant" is from 1814, from the "family tree" image.
sciophobia (n.): "fear of shadows," 1977, from scio-, Latinized comb. form of Greek skia "shade, shadow" (see shine (v.)) + -phobia. Related: sciophobe; sciophobic.
scirrhous (n.): 1560s, from French scirrheux (16c., Modern French squirreux), from Modern Latin scirrhosus, from Latin scirros "a hard swelling, tumor," from Greek skirrhos "hard tumor," from skiros (adj.) "hard," of unknown origin.
scissor (v.): 1610s, “to cut with scissors; 1960s with reference to leg motions (in the wrestling sense it is attested from 1968); see scissors.
scissors (n.): late 14c., sisoures, from Old French cisoires (plural) "shears," from Vulgar Latin *cisoria (plural) "cutting instrument," from *cisus (in compounds such as Latin excisus, past participle of excidere "to cut out"), ultimately from Latin caedere "to cut" (see -cide). Spelling with sc- is 16c., from influence of Medieval Latin scissor "tailor," in classical Latin "carver, cutter," from past participle stem of scindere "to split."

Usually with pair of (attested from c.1400) when indication of just one is required, but a singular form without the -s was occasionally used (mid-15c., cysowre). In Scotland, shears answers for all sizes; but in England generally that word is used only for those too large to be worked by one hand. Sense in wrestling is from 1904. Oh scissors! was a 19c. exclamation of impatience or disgust.
SCLC: initialism of Southern Christian Leadership Conference, founded 1957 by the Rev. Martin Luther King Jr., Bayard Rustin, and others.
sclera (n.): Medical Latin, from Greek sklera (menix) "the hard (membrane)," fem. of skleros "hard" (see sclerosis).
scleroderma (n.): 1866, from Modern Latin, from Greek skleros "hard" (see sclerosis) + derma "skin" (see derma).
sclerosis (n.): "morbid hardening of the tissue," late 14c., from Medieval Latin sclirosis "a hardness, hard tumor," from Greek sklerosis "hardening," from skleros "hard," related to skellein "to dry up, parch," from PIE *skle-ro-, from root *skele- "to parch, wither."
sclerotic (adj.): 1540s, from medical Latin scleroticus, from Greek skleroun (see sclerosis). Meaning "unchanging, rigid" is from 1961.
scoff (v.): late 14c., earlier as a noun, "contemptuous ridicule" (c.1300), from a Scandinavian source, cf. Old Norse skaup, skop "mockery," Middle Danish skof "jest, mockery;" perhaps from Proto-Germanic *skub-, *skuf- (cf. Old English scop "poet," Old High German scoph "fiction, sport, jest, derision;" see scold), from PIE *skeub- "to shove."