Online Etymology Dictionary

sluice (n.): mid-14c., a shortening of Old French escluse "sluice, floodgate," from Late Latin exclusa "barrier to shut out water" (in aqua exclusa "water shut out"), from fem. singular of Latin exclusus, past participle of excludere "shut out" (see exclude).
slum (n.): 1845, from back slum "back alley, street of poor people" (1825), originally a slang word meaning "room," especially "back room" (1812), of unknown origin. Go slumming is from 1884, pastime popularized by East End novels.
slumber (n.): mid-14c., from slumber (v.). Slumber party first recorded 1942.
slumber (v.): mid-14c., alteration of slumeren (early 13c.), frequentative form of slumen "to doze," probably from Old English sluma "light sleep" (cf. Middle Dutch slumen, Dutch sluimeren, German schlummern "to slumber"). Frequentative on the notion of "intermittent light sleep." Related: Slumbered; slumbering.
slumlord (n.): also slum-lord, 1899, from slum landlord (1885); see slum (n.) + landlord.
slump (v.): 1670s, "fall or sink into a muddy place," probably from a Scandinavian source, cf. Norwegian and Danish slumpe "fall upon," Swedish slumpa; perhaps ultimately of imitative origin. Related: Slumped; slumping.
The word "slump," or "slumped," has too coarse a sound to be used by a lady. [Eliza Leslie, "Miss Leslie's Behaviour Book," Philadelphia, 1839]
slump (n.): "heavy decline in prices on the stock exchange," 1888, from slump (v.). Generalized to "sharp decline in trade or business" 1922.
slur (n.): "deliberate slight," c.1600, from dialectal slur "thin or fluid mud," from Middle English slore (mid-15c.), cognate with Middle Low German sluren, Middle Dutch sloren "to trail in mud." Related to East Frisian sluren "to go about carelessly," Norwegian slora "to be careless." The musical sense (1746) is from the notion of "sliding."
slurp (v.): 1640s, from Dutch slurpen, perhaps of imitative origin (cf. German schlurfen). Related: Slurped; slurping. The noun is first recorded 1949.
slurry (n.): mid-15c., "mud, slime," probably related to Middle English sloor "thin or fluid mud" (see slur).
slush (n.): 1640s, perhaps from a Scandinavian source (cf. Norwegian and Swedish slask "slushy ground;" obsolete Danish slus "sleet"), all probably imitative of the sound of sloshing. Slush fund is first attested 1839, from an earlier sense of slush "refuse fat" (1756); the money from the sale of a ship's slush was distributed among the officers, which was the original sense of the phrase. The extended meaning "money collected for bribes and to buy influence" is first recorded 1874, no doubt with suggestions of "greasing" palms.
slushy (adj.): 1791, "covered with slush," from slush + -y (2). As slang for "ship's cook," 1859. Related: Slushiness.
slut (n.): c.1400, "a dirty, slovenly, or untidy woman," probably cognate with dialectal German Schlutt "slovenly woman," dialectal Swedish slata "idle woman, slut," and Dutch slodder "slut," but the ultimate origin is doubtful. Chaucer uses sluttish (late 14c.) in reference to the appearance of an untidy man. Also "a kitchen maid, a drudge" (mid-15c.; hard pieces in a bread loaf from imperfect kneading were called slut's pennies, 18c.). Meaning "woman of loose character, bold hussy" is attested from mid-15c.; playful use of the word, without implication of loose morals, is attested from 1660s.
Our little girl Susan is a most admirable slut, and pleases us mightily. [Pepys, diary, Feb. 21, 1664]
Sometimes used 19c. as a euphemism for bitch to describe a female dog. There is a group of North Sea Germanic words in sl- that mean "sloppy," and also "slovenly woman," and that tend to evolve toward "woman of loose morals" (cf. slattern, also English dialectal slummock "a dirty, untidy, or slovenly person," 1861; Middle Dutch slore "a sluttish woman").
slutty (adj.): c.1400, "slovenly," from slut + -ish. Sluttish is from late 14c.
sly (adj.): c.1200, from Old Norse sloegr "cunning, crafty, sly," from Proto-Germanic *slogis (cf. Low German slu "cunning, sly"), probably from base *slog- "hit" (see slay), with an original notion of "able to hit." Cf. German verschlagen "cunning, crafty, sly," schlagfertig "quick-witted," literally "ready to strike," from schlagen "to strike." A non-pejorative use of the word lingered in northern English dialect until 20c. On the sly "in secret" is recorded from 1812. Sly-boots "a seeming Silly, but subtil Fellow" is in the 1700 "Dictionary of the Canting Crew."
smack (n.1): "taste, flavor," now mainly in verbal figurative use smacks of ... (first attested 1590s; smack as a verb in this sense is from late 14c.), from Old English smæc, from Proto-Germanic *smak- (cf. Old Frisian smek, Dutch smaak, Old High German smac, German Geschmack); probably related to Lithuanian smaguriai "dainties," smagus "pleasing." Meaning "a trace (of something)" is attested from 1530s.
smack (n.3): "heroin," 1942, American English slang, probably an alteration of schmeck "a drug," especially heroin (1932), from Yiddish schmeck "a sniff."
smack (v.1): "make a sharp noise with the lips," 1550s, probably of imitative origin (see smack (v.2)). Meaning "a loud kiss" is recorded from c.1600. With adverbial force, attested from 1782; extended form smack-dab is attested from 1892, American English colloquial.
smack (n.2): "single-masted sailboat," 1610s, probably from Dutch or Low German smak "sailboat," from smakken "to fling, dash" (see smack (v.2)), perhaps so-called from the sound made by its sails. French semaque, Spanish zumaca, Italian semacca probably are Germanic borrowings.
smack (v.2): "to slap with the hand," 1835, from noun in this sense (c.1746), perhaps influenced by Low German smacken "to strike, throw," which is likely of imitative origin (cf. Swedish smak "slap," Middle Low German smacken, Frisian smakke, Dutch smakken "to fling down," Lithuanian smagiu "to strike, knock down, whip").
smacker (n.): "money," c.1918, American English slang, perhaps from smack (v.1) on notion of something "smacked" into the palm of the hand. Extended form smackeroo is attested from 1940.
smaik (n.): "mean or contemptible fellow," Scottish, now archaic, current c.1450-c.1900, perhaps cognate with Old High German smeichari, from smeken "to flatter."
small (adj.): Old English smæl "slender, narrow, small," from Proto-Germanic *smalaz (cf. Old Saxon, Danish, Swedish, Middle Dutch, Dutch, Old High German smal, Old Frisian smel, German schmal "narrow," Gothic smalista "smallest," Old Norse smali "small cattle, sheep"), perhaps from a PIE root *(s)melo- "smaller animal" (cf. Greek melon, Old Irish mil "a small animal;" Old Church Slavonic malu "bad"). Original sense of "narrow" now almost obsolete, except in reference to waistline and intestines.
My sister ... is as white as a lilly, and as small as a wand. [Shakespeare, "Two Gentlemen of Verona," 1591]
Sense of "not large, of little size" developed in Old English With many extended senses, e.g. small fry, first recorded 1690s of little fish, 1885 of insignificant people. Small potatoes first attested 1940; small change "something of little value" is from 1902; small talk "chit-chat" (1751) first recorded in Chesterfield's "Letters." Small world as a comment upon an unexpected meeting of acquaintances is recorded from 1895. Small-town (adj.) "unsophisticated, provincial" is recorded from 1824. Small arms, indicating those capable of being carried in the hand (contrasted to ordnance) is recorded from 1710.
small beer (n.): 1560s, originally "weak beer;" used figuratively of small things or trifling matters. Small with the meaning "of low alcoholic content" is attested from mid-15c.
small-time (adj.): 1910, originally theater slang for lower-salaried circuits, or ones requiring more daily performances.
smallpox (n.): 1510s, small pokkes, as distinguished from great pox "syphillis" (see pox). Cf. French petite vérole.
smarm (n.): 1914, from colloquial verb smalm, smarm "to smear, bedaub" (the hair, with pomade), 1847, of unknown origin. Verbal meaning "to smear with flattery" is from 1902.
smarmy (adj.): "ingratiating, unctuous," 1924, from smarm + -y (2).
smart (v.): Old English smeortan "be painful," from West Germanic *smert- (cf. Middle Dutch smerten, Dutch smarten, Old High German smerzan, German schmerzen "to pain," originally "to bite"), from PIE *(s)merd-, from root *(s)mer- "to rub, pound" (cf. Greek smerdnos "terrible, dreadful," Sanskrit mardayati "grinds, rubs, crushes," Latin mordere "to bite").
smart (adj.): late Old English smeart "sharp, severe, stinging," related to smeortan (see smart (v.)). Meaning "quick, active, clever" is attested from c.1300, probably from the notion of "cutting" wit, words, etc.; meaning "trim in attire" first attested 1718, "ascending from the kitchen to the drawing-room c.1880." [Weekley]

In reference to devices, "behaving as though guided by intelligence" (e.g. smart bomb) first attested 1972. Smarts "good sense, intelligence," is first recorded 1968. Smart cookie is from 1948; smarty-pants first attested 1941.
smart aleck (n.): 1865, perhaps in reference to Aleck Hoag, notorious pimp, thief, and confidence man in New York City in early 1840s.
smart money (n.): "money bet by those in the know," 1926, from smart (adj.). The same phrase earlier meant "money paid to sailors, soldiers, workers, etc., who have been disabled while on the job" (1690s), from a noun derivative of smart (v.).
smartass: also smart ass, 1960 (adj.), 1962 (n.), from smart (adj.) + ass (2).
smarten (v.): "to make smart, to spruce up, to improve appearance," 1815 (in "Emma"), from smart (adj.) + -en (1). Related: Smartened; smartening.
smartmouth (n.): 1968, from smart (adj.) + mouth (n.).
smash (v.): 1778, "break to pieces," earlier "kick downstairs" (c.1700), probably of imitative origin (cf. smack, mash). Smash-up "collision" is recorded from 1856; smash-and-grab is first attested 1927.
smash (n.): 1839, "failure, financial collapse," from smash (v.). Tennis sense is from 1882. Meaning "great success" is from 1923 ("Variety" headline, Oct. 16, in reference to Broadway productions of "The Fool" and "The Rise of Rosie O'Reilly").
smashed (adj.): "drunk," slang, 1962, from past participle of smash (v.).
smashing (adj.): "pleasing, sensational," 1911, from present participle of smash (v.). Related: Smashingly.
smatter (v.): early 15c., "talk idly, chatter," perhaps imitative. Similar forms are found in Middle High German smetern "to chatter" and Swedish smattra "to patter, rattle." Related: Smattered; smattering.
smatterer (n.): "one who has superficial knowledge," 1510s, agent noun from smatter (v.).
smear (n.): "mark or stain left by smearing," 1610s, from smear (v.). Sense of "small quantity prepared for microscopic examination" is from 1903.
smear (v.): Old English smerian "to anoint or rub with grease, oil, etc.," from Proto-Germanic *smerthan (cf. Old Norse smyrva, Danish smøre, Swedish smörja, Dutch smeren, Old High German smirwen, German schmieren "to smear"), from PIE *smeru- "grease" (cf. Greek myron "unguent, balsam," Old Irish smi(u)r "marrow," Old English smeoru "fat, grease"). Sense of "assault a public reputation with unsubstantiated charges" is from 1879. Related: Smeared; smearing.
smegma (n.): 1819, from Latin, from Greek smegma "a detergent," from smekhein "to wipe off, wipe clean, cleanse," from PIE root *(s)mei- "to rub" (cf. Czech smetana "cream").
smell (n.): "odor, aroma, stench," late 12c.; see smell (v.). Ousted Old English stenc (see stench) in most senses.
smell (v.): late 12c., "emit or perceive an odor," not found in Old English, perhaps cognate with Middle Dutch smolen, Low German smelen "to smolder" (see smolder). OED says "no doubt of Old English origin, but not recorded, and not represented in any of the cognate languages."

Someone should revive smell-feast (n.) "one who scents out where free food is to be had" (1510s, "very common" c.1540-1700, OED) and smell-smock "licentious man" (c.1550-1900). To smell a rat "be suspicious" is from 1540s.
smelly (adj.): 1862, from smell + -y (2). Related: Smelliness.
smelt (v.): mid-15c. (implied in smelter), from Dutch or Low German smelten, cognate with Old High German smelzan, German schmelzen "to melt;" apparently a variant of the stem of Old English meltan "to melt" (see melt). Related: Smelted; smelting.
smelt (n.): Old English smelt "small salmon-like sea fish," cognate with Dutch smelt "sand eel," Danish smelt (c.1600). OED notes that it has a peculiar odor (but doesn't suggest a connection with smell); Klein suggests a connection with the way the fish melts in one's mouth.
smelter (n.): mid-15c., agent noun from smelt (v.).