swat (v.)
1796, American English and northern England dialect word, possibly an alteration of Middle English swap "to strike, smite" (see swap), ultimately of imitative origin. Related: Swatted; swatting. The noun is recorded from 1800.
swatch (n.)
1510s, "the countercheck of a tally" (Northumberland dialect), later "a tally attached to cloth sent to be dyed" (1610s, in Yorkshire), of unknown origin. Century Dictionary compares swath. Meaning "a sample piece of cloth" is from 1640s.
swath (n.)
Old English swæð, swaðu "track, footstep, trace, scar, vestige," from Proto-Germanic *swathan, *swatho (cognates: Old Frisian swethe "boundary made by a scythe," Middle Dutch swade, Dutch zwade, German Schwad "a row of cut grass"); of uncertain origin. Meaning "a mown crop lying on the ground" is from early 14c.; that of "space covered by the single cut of a scythe" emerged late 15c., and that of "a strip, lengthwise extent" is from c.1600.
swathe (v.)
"to bind with bandages, swaddle, wrap," Old English swaþian "to swathe, wrap up," from swaðu "track, trace" (see swath). The noun meaning "infant's swaddling bands" was found in Old English as swaþum (dative plural). Related: Swathed; swathing.
swatter (n.)
"instrument for swatting flies," 1906, agent noun from swat (v.).
sway (v.)
early 14c., "move, go, go quickly; move (something) along, carry," probably from a Scandinavian source akin to Old Norse sveigja "to bend, swing, give way," Old Danish svegja, perhaps merged with an unrecorded Old English cognate. The whole group might be related to swag (v.) and swing (v.).

The sense of "swing, waver, move in a swaying or sweeping motion" is from late 14c. Meaning "move from side to side" is from c.1500; transitive sense "cause to move from side to side" is from 1550s (according to OED, not common before 19c.). Figurative sense "cause to be directed toward one side, prejudice" is from 1590s. Related: Swayed; swaying.
sway (n.)
c.1300, "movement from side to side," from sway (v.). The meaning "controlling influence" (as in to be under the sway of) is from 1510s, from a transitive sense of the verb in Dutch and other languages.
sway-backed (adj.)
1670s, according to OED of Scandinavian origin, perhaps related to obsolete Danish sveibaget. See sway (v.) + back (n.).
swear (v.)
Old English swerian "take an oath" (class VI strong verb; past tense swor, past participle sworen), from Proto-Germanic *swarjan-, (cognates: Old Saxon swerian, Old Frisian swera, Old Norse sverja, Danish sverge, Middle Dutch swaren, Old High German swerien, German schwören, Gothic swaren "to swear"), from PIE root *swer- (1) "to speak, talk, say" (cognates: Old Church Slavonic svara "quarrel," Oscan sverrunei "to the speaker").

Also related to the second element in answer. The secondary sense of "use bad language" (early 15c.) developed from the notion of "invoke sacred names." Swear off "desist as with a vow" is from 1898. Swear in "install in office by administration of an oath" is from 1700 in modern use, echoing Old English.
swear-word (n.)
1873, American English colloquial, from swear (v.) + word (n.).
swearing (n.)
"utterance of profane language," mid-14c., verbal noun from swear (v.).
sweat (v.)
Old English swætan "perspire," also "work hard," from Proto-Germanic *swaitjan "to sweat," from the source of sweat (n.). Compare Frisian swette, Dutch zweeten, Danish svede, German schwitzen. Meaning "to be worried, vexed" is recorded from c.1400. Transitive sense is from late 14c. Related: Sweated; sweating. Sweating sickness was a sudden, often-fatal fever, accompanied by intense sweating, that struck England 1485 and returned periodically through mid-16c., described in the original citation (a chronicle from 1502) as "a grete deth and hasty."
sweat (n.)
Old English swat "perspiration, moisture exuded from the skin," also "labor, that which causes sweat," from Proto-Germanic *swaitaz "sweat" (cognates: Old Saxon, Old Frisian swet, Old Norse sveiti, Danish sved "sweat," Swedish svett, Middle Dutch sweet, Dutch zweet, Old High German sweiz, German Schweiß), from PIE *sweid- (2) "to sweat" (cognates: Sanskrit svedah "sweat," Avestan xvaeda- "sweat," Greek hidros "sweat, perspiration," Latin sudor, Lettish swiedri, Welsh chwys "sweat").

A widespread set of Slavic words (Polish, Russian pot "sweat") is from Old Church Slavonic potu, related to peku "heat," cognate with Latin coquere.

The Old English noun became Middle English swote, but later altered to the current form under the influence of the verb. Sweat of (one's) brow as a symbol of toil is from Gen. iii:19. Sweat equity is from 1968. Colloquial no sweat "no problem" attested from 1963.
sweat-bee (n.)
1870, American English, from sweat (n.) + bee (n.).
sweater (n.)
"woolen vest or jersey, originally worn in rowing," 1882, from earlier sweaters "clothing worn to produce sweating and reduce weight" (1828), plural agent noun from sweat (v.). As a fashion garment, attested from 1925. Earlier it meant "one who works hard" (1520s). Sweater girl is attested from 1940; Lana Turner (1920-1995) was the first, from her appearance in the film "They Won't Forget" (1937).
sweatpants (n.)
also sweat-pants, 1946, from sweat (v.) + pants (n.).
sweatshirt (n.)
also sweat-shirt, 1921, from sweat (v.) + shirt. Related: Sweatshirted.
sweatshop (n.)
also sweat-shop, 1892, from sweat (v.) + shop (n.). The verb sweat is attested from 1879 in the sense "employ (someone) in hard work for low wages," and compare sweater "one who exacts wages at very low prices" (1846).
sweaty (adj.)
late 14c., "causing sweat;" 1580s, "soaked with sweat," from sweat (n.) + -y (2). Related: Sweatiness.
Swede (n.)
"native of Sweden," 1610s, from Low German, from Middle Low German Swede, from a source akin to Old English Sweoðeod, literally "Swede-people," from Sweon (plural) "Swedes" (Old Norse, Old Swedish Sviar), called by the Romans Suiones, probably from Proto-Germanic *sweba "free, independent," or else from *geswion "kinsman."
Sweden
c.1600, originally in Scottish (Swethin, Swadne, etc.), from Middle Dutch Sweden, probably a dative plural of Swede (earlier in English Sweden was used of the people and until 17c. Swedeland was the English name of the country). In Old English, the country was Sweoland or Sweorice (compare Old Norse sviariki, source of Swedish Sverige). Ultimately named for the original inhabitants (see Swede).
Swedenborgian
1791, from name of Emanuel Svedberg, Swedish mystic and religious philosopher (1668-1772). His followers organized 1788 as The New Church.
Swedish (adj.)
c.1600, from Swede + -ish. Similar formation in Dutch Zweedsch, German Schwedisch. Related: Swedishness. As a language name from c.1600. The candy Swedish fish attested by that name by 1983.
sweep (v.)
early 14c., "make clean by sweeping with a broom;" mid-14c., "perform the act of sweeping," of uncertain origin, perhaps from a past tense form of Middle English swope "sweep," from Old English swapan "to sweep" (transitive & intransitive); see swoop (v.), or perhaps from a Scandinavian source. Related: Swept; sweeping.

From late 14c. as "hasten, rush, move swiftly and strongly;" also "collect by sweeping." From c.1400 in transitive sense "drive quickly, impel, move or carry forward by force;" mid-15c. as "clear (something) away." Meaning "win all the events" is 1960, American English. Sense of "pass systematically over in search of something" is from 1966. To sweep (someone) off (his or her) feet "affect with infatuation" is from 1913.
sweep (n.)
mid-13c., "stroke, force," from sweep (v.). Meaning "act of sweeping" is from 1550s. From 1670s as "range, extent of a continued motion." In reference to police or military actions, it is attested from 1837. Sense of "a winning of all the tricks in a card game" is from 1814 (see sweepstakes); extended to other sports by 1960. Meaning "rapid survey or inspection" is from 1966. As a shortened form of chimney-sweeper, first attested 1796.
sweeper (n.)
1520s, agent noun from sweep (v.). As a position in soccer (association football) by 1964.
sweepstakes (n.)
"prize won in a race or contest," 1773, from Middle English swepestake "one who sweeps or wins all the stakes in a game" (late 14c. as a surname or nickname; late 15c. as the name of one of the King's ships), from swepen "to sweep" (see sweep (v.)) + stake (n.2). Meaning "any race for stakes contributed" is from 1862.
sweet (adj.)
Old English swete "pleasing to the senses, mind or feelings; having a pleasant disposition," from Proto-Germanic *swotja- (cognates: Old Saxon swoti, Old Frisian swet, Swedish söt, Danish sød, Middle Dutch soete, Dutch zoet, Old High German swuozi, German süß), from PIE root *swad- "sweet, pleasant" (Sanskrit svadus "sweet;" Greek hedys "sweet, pleasant, agreeable," hedone "pleasure;" Latin suavis "pleasant" (not especially of taste), suadere "to advise," properly "to make something pleasant to"). Words for "sweet" in Indo-European languages typically are used for other sense as well and in general for "pleasing."
Then come kiss me, sweet-and-twenty!
Youth's a stuff will not endure.
["Twelfth Night"]
Also "being in a sound or wholesome state" (mid-13c.), and, of water, "fresh, not salt" (late Old English). As an intensifier from 1958. Sweet in bed (c.1300) was the equivalent of modern "good in bed." To be sweet on someone is first recorded 1690s. Sweet sixteen first recorded 1767. Sweet dreams as a parting to one going to sleep is attested from 1898, short for sweet dreams to you, etc. Sweet-and-sour in cookery is from 1723 and not originally of oriental food. Sweet nothings "sentimental trivialities" is from 1900. Sweet spot is from 1976, first in reference to tennis rackets. Sweet corn is from 1640s.
sweet (n.)
c.1300, "something sweet to the taste," also "beloved one," from sweet (adj.); the specific meaning "candy drop" is 1851 (earlier sweetie, 1721). Meaning "one who is dear to another" is from 14c. Old English swete (n.) meant "sweetness."
Sweet Adeline
female barbershop singing group member, 1947, from the name of a popular close harmony song by Richard Armstrong & Harry Gerard, "You're the Flower of my Heart, Sweet Adeline" (1903).
sweet tooth (n.)
"fondness for sugary stuff," late 14c., from sweet (adj.) + tooth in the sense of "taste, liking" (see toothsome).
sweet-briar (n.)
"eglantine," 1530s, from sweet (adj.) + briar (n.).
sweet-grass (n.)
1570s, from sweet (adj.) + grass (n.). Perhaps so called for the fondness of cattle for it.
sweet-pea (n.)
1732, from sweet (adj.) + pea (n.).
sweet-talk (v.)
Sweet-talk, 1935, from noun phrase; see sweet (adj.) + talk (n.). Earliest usages seem to refer to conversation between black and white in segregated U.S.
"I ain' gonna stay heah no longah. Don' nevah keer, ef I do git cotched--or die. Tha's bettah than to stay heah an' listen to Maw Haney sweet-talk the white folks, whilst they drives us clean to the grave. ..." ["The Crisis," July 1935]
Latin had suaviloquens, literally "sweet-spoken."
sweetbread (n.)
"pancreas of an animal used as food" 1560s, from sweet (adj.); the -bread element may be from Old English bræd "flesh."
sweeten (v.)
1550s (intransitive), from sweet (adj.) + verbal ending -en (1). Transitive sense ("become sweet") is from 1620s. The Middle English form of the verb was simply sweet, from Old English swetan. Related: Sweetened; sweetening.
sweetener (n.)
1640s, agent noun from sweeten (v.).
sweetheart (n.)
late 13c. as a form of address, 1570s as a synonym for "loved one;" from sweet (adj.) + heart. As an adjective, with reference to labor contracts, it is attested from 1959.
sweetie (n.)
1721, "lollipop;" 1778, "lover, sweetheart," from sweet (n.) + -ie.
sweetly (adv.)
Old English swetlice; see sweet (adj.) + -ly (2).
sweetmeat (n.)
"a sweet thing to eat," Old English swete mete; see sweet (adj.) + meat (n.).
sweetness (n.)
Old English swetnes; see sweet (adj.) + -ness.
swell (v.)
Old English swellan "grow or make bigger" (past tense sweall, past participle swollen), from Proto-Germanic *swelnan (cognates: Old Saxon swellan, Old Norse svella, Old Frisian swella, Middle Dutch swellen, Dutch zwellen, Old High German swellan, German schwellen), of unknown origin. Of emotions from late 14c., of music from 1749. Related: swelled; swollen; swelling.
swell (n.)
c.1200, "a morbid swelling," from swell (v.). In reference to a rise of the sea, it is attested from c.1600; of music, by 1803. The meaning "wealthy, elegant person" is first recorded 1786, connected to the now-obsolete sense "pompousness, arrogance" (1724), both from the notion of "puffed-up" demeanor or behavior.
swell (adj.)
"fashionably dressed or equipped," 1810, from swell (n.) in the "stylish person" sense. As "good, excellent," by 1897; as a stand-alone expression of satisfaction it is recorded from 1930 in American English.
swelling (n.)
"tumor, morbid enlargement," Old English; verbal noun from swell (v.).
swelter (v.)
c.1400, "faint with heat," frequentative of swelten "be faint (especially with heat)," late 14c., from Old English sweltan "to die, perish," from Proto-Germanic *swiltan- (cognates: Old Saxon sweltan "to die," Old Norse svelta "to put to death, starve," Gothic sviltan "to die"), perhaps originally "to burn slowly," hence "to be overcome with heat or fever," from PIE root *swel- (2) "to shine, beam" (see Selene). From the same ancient root comes Old English swelan "to burn." For specialization of words meaning "to die," compare starve. Related: Sweltered; sweltering.
swelter (n.)
"a sweltering condition," 1851, from swelter (v.).
sweltering (adj.)
"oppressively hot" (of weather, seasons), 1590s, present participle adjective from swelter (v.). Related: Swelteringly.