Online Etymology Dictionary

skeletal (adj.): 1849, from skeleton + -al (1). Related: Skeletally.
skeleton (n.): 1570s, from Modern Latin sceleton "bones, bony framework of the body," from Greek skeleton soma "dried-up body, mummy, skeleton," from neuter of skeletos "dried-up" (also, as a noun, "dried body, mummy"), from skellein "dry up, make dry, parch," from PIE root *skele- "to parch, wither" (see sclero-).

Skelton was an early variant form. The noun use of Greek skeletos passed into Late Latin (sceletus), hence French squelette and rare English skelet (1560s), Spanish esqueleto, Italian scheletro. The meaning "bare outline" is first recorded c. 1600; hence skeleton crew (1778), skeleton key, etc. Phrase skeleton in the closet "source of secret shame to a person or family" is from 1812 (the image is perhaps from the Bluebeard fable).
skelm (n.): also skellum, "a rascal, scamp, scoundrel," 1610s, from Dutch schelm, from German schelm "rascal, devil, pestilence, etc.," from Old High German scelmo. Used by Dryden, but "Now arch. (except in S.Africa)" [OED].
skene (n.): ancient type of Celtic dagger found in Ireland, double-edged and leaf-like, 1520s, from Irish Gaelic scian (genitive sceine) "knife," cognate with Gaelic sgian "knife," Welsh ysgien "a slicer," from PIE *skiy-ena-, from root *skei- "to divide, split" (see shed (v.)).
skep (n.): quantity measure for grain, etc.; basket, grain receptacle, c. 1100, from Old Norse skeppa "basket, bushel." Related: Skepful.
skeptic (n.): also sceptic, 1580s, "member of an ancient Greek school that doubted the possibility of real knowledge," from Middle French sceptique and directly from Latin scepticus "the sect of the Skeptics," from Greek skeptikos (plural Skeptikoi "the Skeptics, followers of Pyrrho"), noun use of adjective meaning "inquiring, reflective" (the name taken by the disciples of the Greek philosopher Pyrrho, who lived c. 360-c. 270 B.C.E.), related to skeptesthai "to reflect, look, view" (see scope (n.1)).
Skeptic does not mean him who doubts, but him who investigates or researches as opposed to him who asserts and thinks that he has found. [Miguel de Unamuno, "Essays and Soliloquies," 1924]
The extended sense of "one with a doubting attitude" first recorded 1610s. The sk- spelling is an early 17c. Greek revival and is preferred in U.S. As a verb, scepticize (1690s) failed to catch on.
skeptical (adj.): also sceptical, 1630s; see skeptic + -al (1). Related: Skeptically.
skepticism (n.): also scepticism, 1640s, from skeptic + -ism. Specifically regarding Christian religion, from 1800.
skerry (n.): "isolated rock in the sea," 1610s, from Old Norse sker, related to skera "to cut off" (see shear (v.)).
sketch (n.): "rough drawing intended to serve as the basis for a finished picture," 1660s, from Dutch schets or Low German skizze, both apparently 17c. artists' borrowings from Italian schizzo "sketch, drawing," which is commonly said to be from Latin *schedius (OED compares schedia "raft," schedium "an extemporaneous poem"), from or related to Greek skhedios "temporary, extemporaneous, done or made off-hand," related to skhema "form, shape, appearance" (see scheme (n.)). But according to Barnhart Italian schizzo is a special use of schizzo "a splash, squirt," from schizzare "to splash or squirt," of uncertain origin.

Extended sense of "brief account" is from 1660s; meaning "short play or performance, usually comic" is from 1789. Sketch-book recorded from 1820. German Skizze, French esquisse, Spanish esquicio are likewise from Italian schizzo.
sketch (v.): 1690s, "present the essential facts of," from sketch (n.). Meaning "draw, portray in outline and partial shading" is from 1725. Related: Sketched; sketcher; sketching.
sketchy (adj.): 1805, "having the form or character of a sketch," from sketch (n.) + -y (2). Colloquial sense of "unsubstantial, imperfect, flimsy" is from 1878, perhaps via the notion of "unfinished." Related: Sketchily; sketchiness.
skew (v.): late 15c., "to turn aside" (intransitive), from Old North French eskiuer "shy away from, avoid," Old French eschiver (see eschew). Transitive sense of "turn (something) aside" is from 1570s. Meaning "depict unfairly" first recorded 1872, on notion of being "give oblique direction to," hence "to distort, to make slant." Statistical sense dates from 1929. Related: Skewed; skewing. The adjectival meaning "slanting, turned to one side" is recorded from c. 1600, from the verb; noun meaning "slant, deviation" first attested 1680s.
skewbald (adj.): 1650s, "having white and brown (or some other color) patches, spotted in an irregular manner" (used especially of horses), from skued "skewbald" (mid-15c.), of unknown origin, + bald "having white patches" (see bald). First element said to be unconnected with skew (v.) (but Klein's sources say it is); OED suggests perhaps from Old French escu "shield," but also notes a close resemblance in form and sense with Icelandic skjottr, "the history of which is equally obscure." Watkins says it is Scandinavian and akin to Old Norse sky "cloud" on the resemblance of the markings to cloud cover.
When the white is mixed with black it is called 'pie-bald,' with bay the name of 'skew-bald' is given to it. ["Youatt's 'The Horse,' " 1866]
As a noun meaning "skewbald horse" from 1863.
skewer (n.): 1670s, variant of dialectal skiver (1660s), perhaps from a Scandinavian source such as Old Norse skifa "a cut, slice" (of bread, etc.), Swedish skifer "a slate," which are related to shiver (n.1) "small piece."
skewer (v.): 1701, from the noun. Related: Skewered; skewering.
skewness (n.): 1877, from skew + -ness.
ski (n.): 1883 (there is an isolated instance from 1755; in early use often spelled skee), from Norwegian ski, related to Old Norse skið "long snowshoe," literally "stick of wood, firewood," cognate with Old English scid "stick of wood," obsolete English shide "piece of wood split off from timber;" Old High German skit, German Scheit "log," from Proto-Germanic *skid- "to divide, split," from PIE root *skei- "to cut, split" (see shed (v.)). Ski-jumper is from 1894; ski bum first attested 1960; ski-mask is from 1963; noted as part of criminal disguises from 1968.
ski (v.): 1885, from ski (n.). Related: Skied; skiing.
Ski-doo (n.): proprietary name of a type of snowmobile, 1961, from ski.
ski-lift (n.): by 1949, from ski + lift (n.) in the "hoisting machinery" sense.
skid (v.): 1670s, "apply a skid to (a wheel, to keep it from turning)," from skid (n.). Meaning "slide along" first recorded 1838; extended sense of "slip sideways" (on a wet road, etc.) first recorded 1884. The original notion is of a block of wood for stopping a wheel; the modern senses are from the notion of a wheel slipping when blocked from revolving.
skid (n.): c. 1600, "beam or plank on which something rests," especially on which something heavy can be rolled from place to place (1782), of uncertain origin, probably from a Scandinavian source akin to Old Norse skið "stick of wood" (see ski (n.)). As "a sliding along" from 1890; specifically of motor vehicles from 1903. Skid-mark is from 1914.

In the timber regions of the American West, skids laid down one after another to form a road were "a poor thing for pleasure walks, but admirably adapted for hauling logs on the ground with a minimum of friction" ["Out West" magazine, October 1903]. A skid as something used to facilitate downhill motion led to figurative phrases such as hit the skids "go into rapid decline" (1909), and see skid row.
skid row (n.): place where vagabonds, low-lifes, and out-of-work men gather in a town, 1921, with reference to Seattle, Washington, U.S., a variant of skid road "track of skids along which logs are rolled" (1851); see skid (n.); the sense of which was extended to "part of town inhabited by loggers" (1906), then, by hobos, to "disreputable district" (1915); probably shaded by the notion of "go downhill."
skidoo (v.): a vogue word of 1905, "to leave in a hurry," perhaps a variant of skedaddle (q.v.). The association with twenty-three is as old as the word, but the exact connection is obscure.
Then skidoo, little girl, skidoo.
23 is the number for you.
[1906]
skier (n.): 1895, agent noun from ski (v.).
skiff (n.): "small boat," 1570s, from French esquif (1540s), from Italian schifo "little boat," from a Germanic source (such as Old High German scif "boat;" see ship (n.)). Originally the small boat of a ship.
skiffle (n.): style of U.K. pop music, 1957, from U.S. slang meaning "type of jazz played on improvised instruments" (1926), of unknown origin.
skiing (n.): 1885, verbal noun from ski (v.).
THE new sport which has lately been introduced at Beloit is skeeing. They are long ash planks, carefully and turned up at the end, and are warranted to take down hill quicker than a wink. After some practice performers become very expert, and the speed with which they go is something surprising. [Beloit College, Wisconsin, "Round Table," Dec. 18, 1885]
skill (n.): late 12c., "power of discernment," from Old Norse skil "distinction, ability to make out, discernment, adjustment," related to skilja (v.) "to separate; discern, understand," from Proto-Germanic *skaljo- "divide, separate" (source also of Swedish skäl "reason," Danish skjel "a separation, boundary, limit," Middle Low German schillen "to differ," Middle Low German, Middle Dutch schele "separation, discrimination;" see shell (n.)). Sense of "ability, cleverness" first recorded early 13c.
skilled (adj.): 1550s, past participle adjective from skill (v.) "to have personal and practical knowledge" (c. 1200), from Old Norse skilja "separate, part, divide; break off, break up; part company, take leave; discern, distinguish; understand, find out; decide, settle," from the source of skill (n.).
skillet (n.): c. 1400, of uncertain origin, perhaps from Middle French esculette "a little dish" (Modern French écuelle), diminutive of escuele "plate," from Latin scutella "serving platter" (see scuttle (n.)); or formed in English from skele "wooden bucket or pail" (early 14c.), from a Scandinavian source such as Old Norse skjola "pail, bucket."
skillful (adj.): also skilful, early 14c., from skill + -ful. Related: Skillfully; skilfully.
skim (v.): early 15c. (skimmer, the utensil, is attested from late 14c.), "to clear (a liquid) from matter floating on the surface, lift the scum from," from Old French escumer "remove scum," from escume (Modern French écume) "scum," from a Germanic source (compare Old High German scum "scum," German Schaum; see scum). Meaning "to throw (a stone) so as to skip across the surface of (water) is from 1610s. Meaning "to move lightly and rapidly over the surface of" is from 1650s, from the motion involved in skimming liquid; that of "to glance over carelessly" (in reference to printed matter) recorded by 1799. Related: Skimmed; skimming.
skim-milk (n.): milk from which the cream has been skimmed, 1590s, from skim (v.) + milk (n.).
skimmer (n.): "skimming utensil," late 14c., agent noun from skim (v.). From 1751 as "one who reads superficially." The North American shore bird (1785) is so called from its method of feeding. As "one who diverts money from earnings for some private purpose" by 1970.
skimp (v.): 1879, probably a back-formation of skimpy. Related: Skimped; skimping.
skimpy (adj.): 1842, from skimp (adj.) "scanty" (1775), which perhaps ultimately is from an early 18c. alteration of scrimp or a variant of scamp (v.). Related: Skimpiness.
skin (n.): c. 1200, "animal hide" (usually dressed and tanned), from Old Norse skinn "animal hide, fur," from Proto-Germanic *skintha- (source also of Old English scinn (rare), Old High German scinten, German schinden "to flay, skin;" German dialectal schind "skin of a fruit," Flemish schinde "bark"), from PIE *sken- "to cut off" (source also of Breton scant "scale of a fish," Irish scainim "I tear, I burst"), from root *sek- "to cut" (see section (n.)).
Ful of fleissche Y was to fele, Now ... Me is lefte But skyn & boon. [hymn, c. 1430]
The usual Anglo-Saxon word is hide (n.1). Meaning "epidermis of a living animal or person" is attested from early 14c.; extended to fruits, vegetables, etc. late 14c. Jazz slang sense of "drum" is from 1927. Meaning "a skinhead" is from 1970. As an adjective, it formerly had a slang sense of "cheating" (1868); sense of "pornographic" is attested from 1968. Skin deep is first attested in this:
All the carnall beauty of my wife, Is but skin-deep. [Sir Thomas Overbury, "A Wife," 1613; the poem was a main motive for his murder]
The skin of one's teeth as the narrowest of margins is attested from 1550s in the Geneva Bible literal translation of the Hebrew text in Job xix:20. To get under (someone's) skin "annoy" is from 1896. Skin-graft is from 1871. Skin merchant "recruiting officer" is from 1792.
skin (v.): late 14c., "to remove the skin from" (originally of circumcision), from skin (n.). As "to have (a particular kind of) skin" from c. 1400. In 19c. U.S. colloquial use, "to strip, fleece, plunder;" hence skin-game, one in which one player has no chance against the others (as with a stacked deck), the type of con game played in a skin-house. Skin the cat in gymnastics is from 1845. Related: Skinned; skinning.
skin-tight (adj.): "fitting like skin," 1885, originally of men's clothing, from skin (n.) + tight (adj.).
skinflint (n.): "miser, one who makes use of contemptible economy to keep money," 1700, slang; literally "kind of person who would skin a flint to save or gain something," from skin (v.) + flint. Flay-flint in same sense is from 1670s.
skinhead (n.): 1969, in U.K. youth gang sense, from skin (n.) + head (n.). Earlier, in U.S., it meant "man with a crew cut" (1953), especially a military recruit.
skink (n.): 1580s, from Middle French scinc (Modern French scinque), from Latin scincus, from Greek skinkos, some kind of lizard common in Asia and North Africa, of unknown origin.
skinless (adj.): mid-14c., from skin (n.) + -less. Related: Skinlessly; skinlessness.
skinner (n.): late 14c., "a dealer in skins," from skin (n.); as "one who skins," 1690s, agent noun from skin (v.). The surname is attested from mid-13c. Also in U.S. use "one who strips, robs, or plunders;" the name given to a band of marauders who committed depredations on Loyalists in New York during the Revolution. Compare Old Norse skinnari "a dealer in skins; a skinner, tanner."
Skinner box (n.): 1940 (earlier Skinner apparatus, 1938), from U.S. psychologist B.F. Skinner (1904-1990).
skinny (adj.): c. 1400, "resembling skin," from skin (n.) + -y (2). Meaning "lean, emaciated" is recorded from c. 1600. Of clothes, "tight-fitting" by 1970. In the noun sense of "the truth" it is World War II military slang, perhaps from the notion of the "naked" truth. Related: skinniness.
skinny-dipping (n.): 1959, from skinny + dip (v.). Skinny-dip is from 1962.
skint (adj.): "broke, out of money," 1925, slang variant of skinned, past participle of skin (v.).