Online Etymology Dictionary

seriously (adv.): c.1500, from serious + -ly (2). To take (something) seriously is from 1782.
sermon (n.): c.1200, from Anglo-French sermun, Old French sermon, from Latin sermonem (nominative sermo) "discourse, speech, talk," originally "a stringing together of words," related to serere "to join" (see series). Main sense in English and French is eliptical for Latin sermo religiosus. Diminutive form sermonette is attested from 1814.
serology (n.): from sero-, comb. form of serum, + -ology.
serotonin (n.): neurotransmitting chemical, 1948, coined from sero-, comb. form of serum (q.v.) + ton(ic) + chemical suffix -in (2).
serous (adj.): 1590s, "of or pertaining to serum," from French séreux (16c.), from Latin serosus, from serum "watery fluid, whey" (see serum).
serpent (n.): c.1300, "limbless reptile," also "tempter in Gen. iii:1-5," from Old French sarpent, from Latin serpentem (nominative serpens) "snake," from present participle of serpere "to creep," from PIE *serp- (cf. Sanskrit sarpati "creeps," sarpah "serpent;" Greek herpein "to creep," herpeton "serpent;" Albanian garper "serpent").
serpentine (n.): c.1400, "plant reputed to contain antivenom," from Old French serpentin (fem. serpentine), from Late Latin serpentius "of a serpent," from Latin serpentem (nominative serpens) "snake" (see serpent). As the name of a greenish igneous rock consisting mainly of hydrous magnesium silicate, attested from early 15c.
serpentine (adj.): "twisting, winding," 1610s; see serpent + -ine (1). An earlier adjective meaning "having the evil qualities of a serpent" is recorded from late 14c. The winding lake of that name in Hyde Park, London, was constructed in 1730.
serrate (adj.): 1660s, from Latin serratus "notched like a saw," from serra "a saw," of unknown origin. Related: Serrated; serrating.
serrated (adj.): 1703, past participle adjective from serrate.
serried (adj.): "pressed close together," 1667 (in "Paradise Lost"), past participle of serry "to press close together" (1580s), a military term, from Middle French serre "close, compact," past participle of serrer "press close, fasten," from Vulgar Latin *serrare "to bolt, lock up," from Latin serare, from sera "bolt, lock." Modern use popularized by Scott.
serum (n.): 1670s, "watery animal fluid," from Latin serum "watery fluid, whey," from PIE root *ser-/*sor- "to run, flow" (cf. Greek oros "whey;" Sanskrit sarah "flowing," sarit "brook, river"). First applied 1893 to blood serum used in medical treatments.
serval (n.): African wild cat, 1771, from Modern Latin serval, French serval (Buffon, 1765), from Portuguese (lobo) cerval "lynx," from Latin lupus cervarius (cf. French loup cervier) "lynx," literally "wolf that hunts the stag," from cervarius "pertaining to a stag," from cervus "stag" (see horn (n.)).
servant (n.): early 13c., from Old French, noun use of servant "serving, waiting," present participle of servir "to attend, wait upon" (see serve). Meaning "professed lover, one devoted to the service of a lady" is from mid-14c. In North American colonies and U.S., the usual designation for "slave" 17c.-18c. (in 14c.-15c. and later in Biblical translations the word often was used to render Latin servus, Greek doulos "slave"). Public servant is attested from 1670s.
serve (v.): late 12c., "to render habitual obedience to," from Old French servir "to serve," from Latin servire "to serve," originally "be a slave," related to servus "slave," perhaps from an Etruscan word (cf. Etruscan proper names Servi, Serve). Meaning "to attend to (a customer)" is first recorded mid-14c.; that of "to set food on (a table)" is from late 14c. Sporting sense, in tennis, badminton, etc., first recorded 1580s; the noun in this sense is from 1680s. To serve (someone) right "to treat as he deserves" is recorded from 1580s. To serve the time "shape one's views to what is in favor" is from 1550s, translating Latin tempori servire; time-server first recorded 1580s. Related: Served. Serving "a helping of food" is from 1769.
server (n.): late 14c., agent noun from serve (v.). Computer sense by 1992.
servery (n.): 1893, from serve + -ery.
service (n.): c.1100, "celebration of public worship," from Old French servise, from Latin servitium "slavery, servitude," from servus "slave" (see serve). Meaning "act of serving" is attested from early 13c. Sense of "duty of a military man" first recorded 1580s, hence "the military as an occupation" (1706). Meaning "the furniture of the table" (tea service, etc.) is from mid-15c. Service industry (as distinct from production) attested from 1941.
service (v.): 1893, "to provide with service," from service (n.). Meaning "perform work on" first recorded 1926. Related: Serviced; servicing.
serviceable (adj.): "ready to do service," early 14c., from Old French serviçable, from servise (see service (n.)).
Edgar: I know thee well: a serviceable villain,
As duteous to the vices of thy mistress
As badness would desire.
["King Lear," Act IV, Scene vi, and "I Am the Walrus"]
servient (adj.): 1640s, from Latin servientem, present participle of servire (see serve).
serviette (n.): "table napkin," late 15c., from French serviette "napkin, towel," perhaps from past participle of servir "to serve" (see serve). Exclusively Scottish at first, re-introduced from French 1818.
servile (adj.): late 14c., from Latin servilis "of a slave, servile," from servus "slave" (see serve). Earliest sense was legal, servile work being forbidden on the Sabbath; sense of "cringing, fawning" first recorded c.1600.
servitude (n.): late 15c., "condition of being enslaved," from Middle French servitude, from Late Latin servitudo "slavery," from Latin servus "a slave" (see serve).
servo: 1910, from servo-motor (1889), from French servo-moteur (1873), ultimately from Latin servus "slave" (see serve) + motor "mover" (see motor).
sesame: mid-15c., probably from Middle French sisame, from Latin sesamum (nominative sesama), from Greek sesamon (Doric sasamon) "seed or fruit of the sesame plant," via Phoenician from Late Babylonian *shawash-shammu (cf. Assyrian shamash-shammu "sesame," literally "oil-seed"). First as a magic password in 1785 translation of Galland's "Mille et une nuits," where it opens the door of the thieves' den in "Ali Baba and the Forty Thieves." Phrase open sesame current since about 1826.
sesquicentennial (adj.): "pertaining to a century and a half," 1880, from Latin sesqui- "one and a half" (from semis "a half" + -que "and") + centennial (q.v.). First recorded reference is to Baltimore's.
sesquipedalian (n.): 1610s, from Latin sesquipedalia verba "words a foot-and-a-half long," in Horace's "Ars Poetica" (97), nicely illustrating the thing he is criticizing, from sesqui- "half as much again" (see sesquicentennial) + pes "foot" (see foot (n.)).
sessile (adj.): 1725, "adhering close to the surface," from Latin sessilis "pertaining to sitting," from sessum, past participle of sedere "to sit" (see sedentary). Meaning "sedentary" first recorded 1860.
session (n.): late 14c., "periodical sitting of a court," from Old French session, from Latin sessionem (nominative sessio) "act of sitting," from past participle stem of sedere "to sit" (see sedentary). Sense of "period set aside for some activity" is first recorded 1920, in bull session, probably from quarter sessions courts (see quarter). Musical sense of "recording occasion in a studio" is from 1927.
sestina (n.): 1838, from Italian, "poem of six-lined stanzas," from sesto "sixth," from Latin sextus (see six). Invented by 12c. Provençal troubadour Arnaut Daniel. The line endings of the first stanza are repeated in different order in the rest, and in an envoi.
set (v.): Old English settan "cause to sit, put in some place, fix firmly," from Proto-Germanic *satjanan (cf. Old Norse setja, Old Frisian setta, Dutch zetten, German setzen), causative form of Proto-Germanic root *set- (cf. Old English sittan "to sit," see sit (v.)).

Confused with sit since early 14c. Of the sun, moon, etc., "to go down," recorded from c.1300. Set-to "bout, fight" is 1743, originally pugilistic slang. Setup "arrangement" is from 1890.
set (adj.): "fixed," from Middle English sett, properly past participle of setten "to set" (see set (v.)). Meaning "ready, prepared" first recorded 1844.
set (n.): "collection of things," mid-15c., from Old French sette "sequence," variant of secte, from Medieval Latin secta "retinue," from Latin secta "a following" (see sect). The word had been earlier used in English in the sense of "religious sect" (late 14c.), which likely is the direct source of some meanings, e.g. "group of persons with shared status, habits, etc." (1680s). Sense of "burrow of a badger" is attested from 1898. That of "scenery for an individual scene in a play, etc." is recorded from 1859. Meaning "group of pieces musicians perform at a club during 45 minutes (more or less) is from c.1925, though it is found in a similar sense in 1580s.
seta: plural setae, 1793, from Latin seta "bristle."
setback (n.): 1670s, "reversal, check to progress," from set (v.) + back (adv.). Meaning "space between a building and a property line" is from 1916. To set (someone) back "cost" is from 1900.
Seth: masc. proper name, Biblical third son of Adam, literally "set, appointed," from Hebrew shith "to put, set."
sett: see set (n.).
settee (n.): "long seat with back and arms," 1716, perhaps a variant of settle (n.), or a diminutive of set (v.) "act of setting."
setter (n.): "one who sets," c.1400, agent noun from set (v.). As a type of dog (originally a type of spaniel), 1570s, so called because the dog is "set" on game.
setting (n.): late 14c., "fact or action of being set or setting," verbal noun from set (v.). In reference to mounts for jewels, etc. from 1815; meaning "background, history, environment" is attested from 1841.
settle (v.): "come to rest," Old English setlan, from setl "a seat" (see settle (n.)). Sense of "establish a permanent residence" first recorded 1620s; that of "decide" is 1620s. Meaning "reconcile" (a quarrel, differences, etc.) perhaps is influenced by Middle English sahtlen "to reconcile," from Old English saht "reconciliation," from Old Norse satt "reconciliation." Related: Settling. Settled "firmly fixed" is attested from 1550s.
settle (n.): "long bench," Old English setl "a seat, position, abode," related to sittan "to sit," from Proto-Germanic *setla- (cf. Middle Low German, Middle Dutch setel, Dutch zetel, German Sessel, Gothic sitls), from PIE *sedla- (cf. Latin sella "seat, chair," Old Church Slavonic sedlo "saddle," Old English sadol "saddle"), from root *sed- "to sit" (see sedentary).
settlement (n.): 1640s, "act of fixing or steadying;" from settle (v.) + -ment. Meaning "colony" is attested from 1690s; that of "payment of an account" is from 1729.
settler (n.): 1590s, "a thing that settles" (a debate, etc.); agent noun from settle. Meaning "a person who moves into a new country" is from 1690s.
seven (n.): Old English seofon, from Proto-Germanic *sebun (cf. Old Saxon sibun, Old Norse sjau, Old Frisian sowen, siugun, Dutch zeven, Old High German sibun, German sieben), from PIE *septm (cf. Sanskrit sapta, Avestan hapta, Hittite shipta, Greek hepta, Latin septem, Old Church Slavonic sedmi, Lithuanian septyni, Old Irish secht, Welsh saith).

Long regarded as a number of perfection (e.g. Seven wonders, seven sleepers, the latter translating Latin septem dormientes, seven against Thebes etc.), but in German a nasty, troublesome woman could be eine böse Sieben "an evil seven" (1662). Magical power or healing skill associated since 16c. with the seventh son ["The seuenth Male Chyld by iust order (neuer a Gyrle or Wench being borne betweene)," Thomas Lupton, "A Thousand Notable Things," 1579]. The typical number for "very great, strong," e.g. seven-league boots in the fairy story of Hop o'my Thumb. The Seven Years' War (1756-63) is also the Third Silesian War.
Seven Champions: 1590s, the national saints of England, Scotland, Wales, Ireland, France, Spain, and Italy, viz. George, Andrew, David, Patrick, Denys, James, and Anthony.
Seven Seas: 1872, the Arctic, Antarctic, North Atlantic, South Atlantic, North Pacific, South Pacific, and Indian.
Seven Sisters: "the Pleiades," early 15c. (see Pleiades), seven daughters of Atlas and Pleione, placed among the stars by Zeus. As a name for the major multi-national petroleum companies, it is attested from 1962. They were listed in 1976 as Exxon, Mobil, Gulf, Standard Oil of California, Texaco, British Petroleum, and Royal Dutch Shell. The Pleiades also are known as the Seven Stars (Old English sibunsterri), though in 15c. and after this name occasionally was given to the Big Dipper (which also has seven stars).
FOOL: ... The reason why the
seven stars are no more than seven is a pretty reason.
KING LEAR: Because they are not eight?
FOOL: Yes, indeed: thou wouldst make a good fool.
["King Lear," Act I, Scene V]
seven-up: children's game, 1830; with capital initials, as the prop. name of a brand of carbonated drink, it is attested from 1928.