Online Etymology Dictionary

secure (v.): c. 1600, "to make safe," from secure (adj.). Meaning "ensure, make certain" is from 1650s; that of "seize and hold" is from 1640s; sense of "get possession" is from 1743. Related: Secured; securing.
security (n.): mid-15c., "condition of being secure," from Latin securitas, from securus "free from care" (see secure). Replacing sikerte (early 15c.), from an earlier borrowing from Latin; earlier in the sense "security" was sikerhede (early 13c.); sikernesse (c. 1200).

Meaning "something which secures" is from 1580s; "safety of a state, person, etc." is from 1941. Legal sense of "property in bonds" is from mid-15c.; that of "document held by a creditor" is from 1680s. Phrase security blanket in figurative sense is attested from 1966, in reference to the crib blanket carried by the character Linus in the "Peanuts" comic strip (1956).
sedan (n.): 1630s, "covered chair on poles," possibly from a southern Italian dialect derivative of Italian sede "chair" (compare Italian seggietta, 1590s; the thing itself was said to have been introduced from Naples), from Latin sedes, related to sedere "sit" (see sedentary). Since Johnson's conjecture, often derived from the town of Sedan in France, where it was said to have been made or first used, but historical evidence for this is lacking.

Introduced in England by Sir Sanders Duncombe in 1634 and first called a covered chair. "In Paris the sedan-chair man was usually an Auvergnat, in London an Irishman" ["Encyclopaedia Britannica," 1929]. Meaning "closed automobile seating four or more" first recorded 1912, American English.
sedate (adj.): "calm, quiet," 1660s, from Latin sedatus "composed, moderate, quiet, tranquil," past participle of sedare "to settle, calm," causative of sedere "to sit" (see sedentary). Related: Sedately.
sedate (v.): "treat with sedatives," 1945, a back-formation from the noun derivative of sedative (adj.). The word also existed 17c. in a sense "make calm or quiet." Related: Sedated; sedating.
sedation (n.): early 15c., "alleviation of pain;" 1540s, "act of making calm," from Middle French sédation and directly from Latin sedationem (nominative sedatio) "a quieting, assuaging, a calming," noun of action from past participle stem of sedare (see sedate (adj.)).
sedative (adj.): "tending to calm or soothe," early 15c., from Medieval Latin sedativus "calming, allaying," from sedat-, past participle stem of sedare, causative of sedere "to sit" (see sedentary). The noun derivative meaning "a sedative drug" is attested from 1785. Hence, "whatever soothes or allays."
sedentary (adj.): 1590s, "remaining in one place," from Middle French sédentaire (16c.) and directly from Latin sedentarius "sitting, remaining in one place," from sedentem (nominative sedens), present participle of sedere "to sit; occupy an official seat, preside; sit still, remain; be fixed or settled," from PIE root *sed- (1) "to sit" (source also of Sanskrit a-sadat "sat down," sidati "sits;" Old Persian hadis "abode;" Greek ezesthai "to sit," hedra "seat, chair, face of a geometric solid;" Old Irish suide "seat, sitting;" Welsh sedd "seat," eistedd "sitting;" Old Church Slavonic sežda, sedeti "to sit;" Lithuanian sedmi "to sit;" Russian sad "garden," Lithuanian soditi "to plant;" Gothic sitan, Old English sittan "to sit;" see sit). Of persons, the sense "not in the habit of exercise" is recorded from 1660s.
Seder (n.): home service on the first nights of Passover, 1865, from Hebrew sedher "order, procedure," related to sedherah "row, rank."
sederunt (n.): "sitting, session," Latin, literally "they sat" (typical opening word in recordings of such proceedings), third person plural past tense of sedere "to sit" (see sedentary).
sedge (n.): "coarse grass-like plant growing in wet places," Old English secg "sedge, reed, rush," from Proto-Germanic *sagjoz (source also of Low German segge, German Segge), probably from PIE root *sek- "to cut" (see section (n.) and compare Old English secg, identical in form but meaning "sword;" and German schwertel-gras "sedge" from schwert "sword"), on notion of plant with "cutting" leaves (compare etymological sense of gladiolus). Old Irish seisg, Welsh hesgreed "rush" might represent a similar sense development from the same root. Often spelled seg, segg until present form triumphed early 1900s.
sediment (n.): 1540s, "matter which settles at the bottom of water or other liquid," from Middle French sédiment (16c.) and directly from Latin sedimentum "a settling, sinking down," from stem of sedere "to settle, sit" (see sedentary).
sedimentary (adj.): 1764, from sediment + -ary. Sedimentary rock attested by 1830 (in Lyell). Sedimental (adj.) is recorded from c. 1600.
sedimentation (n.): 1845, from sediment + -ation.
sedition (n.): mid-14c., "rebellion, uprising, revolt, concerted attempt to overthrow civil authority; violent strife between factions, civil or religious disorder, riot; rebelliousness against authority," from Old French sedicion (14c., Modern French sédition) and directly from Latin seditionem (nominative seditio) "civil disorder, dissention, strife; rebellion, mutiny," literally "a going apart, separation," from se- "apart" (see secret) + itio "a going," from past participle of ire "to go" (see ion).

Meaning "conduct or language inciting to rebellion against a lawful government" is from 1838. An Old English word for it was folcslite. Less serious than treason, as wanting an overt act, "But it is not essential to the offense of sedition that it threaten the very existence of the state or its authority in its entire extent" [Century Dictionary].
seditious (adj.): mid-15c., from Middle French seditieux, from Latin seditiosus "full of discord, factious, mutinous," from seditio (see sedition). Related: Seditiously; seditiousness.
seduce (v.): 1520s, "to persuade a vassal, etc., to desert his allegiance or service," from Latin seducere "lead away, lead astray," from se- "aside, away" (see secret (n.)) + ducere "to lead" (see duke (n.)). Sexual sense, now the prevailing one, is attested from 1550s and apparently was not in Latin. Originally "entice (a woman) to a surrender of chastity." Related: Seduced; seducing.

Replaced Middle English seduisen (late 15c.), from Middle French séduire "seduce," from Old French suduire "to corrupt, seduce," from Latin subducere "draw away, withdraw, remove" (see subduce).
seductible (adj.): 1620s, from seduct-, past participle stem of Latin seducere (see seduce) + -ible. Related: Seductibly; seductibility.
seduction (n.): 1520s, from Middle French séduction, from Latin seductionem (nominative seductio), noun of action from past participle stem of seducere (see seduce). Originally with reference to actions or beliefs; sexual sense is from 1769, originally always with women as the objects. Earlier appearance of the word in Middle English with a sense "treason, treachery" probably is a confusion with sedition, which confusion also is found in Old French seducion "treason, betrayal."
seductive (adj.): 1740, from Latin seduct-, past participle stem of seducere (see seduce) + -ive. Related: Seductively; seductiveness. Middle English had seducious "deceitful, devious" (mid-15c.).
seductress (n.): 1803, "female seducer," with -ess + obsolete seductor (late 15c., displaced by seducer), from a direct borrowing of the Latin agent noun of seducere (see seduce).
sedulity (n.): 1540s, from Latin sedulitas "assiduity, application," noun of quality from sedulus (see sedulous).
sedulous (adj.): 1530s, from Latin sedulus "attentive, painstaking, diligent, busy, zealous," probably from sedulo (adv.) "sincerely, diligently," from sedolo "without deception or guile," from se- "without, apart" (see secret) + dolo, ablative of dolus "deception, guile," cognate with Greek dolos "ruse, snare." Related: Sedulously; sedulousness.
sedum (n.): mid-15c., from Latin sedum "houseleek."
see (v.): Old English seon "to see, look, behold; observe, perceive, understand; experience, visit, inspect" (contracted class V strong verb; past tense seah, past participle sewen), from Proto-Germanic *sekhwan (source also of Old Saxon, Old High German sehan, Middle High German, German sehen, Old Frisian sia, Middle Dutch sien, Old Norse sja, Gothic saihwan), from PIE root *sekw- (2) "to see," which is probably identical with *sekw- (1) "to follow" (see sequel), a root which produced words for "say" in Greek and Latin, and also words for "follow" (such as Latin sequor), but "opinions differ in regard to the semantic starting-point and sequences" [Buck]. Thus see might originally mean "follow with the eyes."

Used in Middle English to mean "behold in the imagination or in a dream" (c. 1200), "to recognize the force of (a demonstration)," also c. 1200. Sense of "escort" (as in to see (someone) home) first recorded 1607 in Shakespeare. Meaning "to receive as a visitor" is attested from c. 1500. Gambling sense of "equal a bet" is from 1590s. See you as a casual farewell first attested 1891. Let me see as a pausing statement is recorded from 1510s.
see (n.): c. 1300, "throne of a bishop, archbishop, or pope," also "throne of a monarch, a goddess, Antichrist, etc.," from Old French sie "seat, throne; town, capital; episcopal see," from Latin sedem (nominative sedes) "seat, throne, abode, temple," related to sedere "to sit" (see sedentary). Early 14c. as "administrative center of a bishopric;" c. 1400 as "province under the jurisdiction of a bishop."
see-saw (n.): also seesaw, 1630s, in see-saw-sacke a downe (like a Sawyer), words in a rhythmic jingle used by children and repetitive motion workers, probably imitative of the rhythmic back-and-forth motion of sawyers working a two-man saw over wood or stone (see saw (n.1). Ha ha.). Reference to a game of going up and down on a balanced plank is recorded from 1704; figurative sense is from 1714. Applied from 1824 to the plank arranged for the game.
see-saw (v.): also seesaw, "move up and down," 1712, from see-saw (n.). Related: See-sawed; see-sawing.
see-through (adj.): 1950, from the verbal phrase (c. 1400); see see (v.) + through (adv.).
seed (n.): Old English sed, sæd "that which may be sown; an individual grain of seed; offspring, posterity," from Proto-Germanic *sediz "seed" (source also of Old Norse sað, Old Saxon sad, Old Frisian sed, Middle Dutch saet, Old High German sat, German Saat), from PIE *se-ti- "sowing," from root *se- (1) "to sow" (see sow (v.)). Figurative use in Old English. Meaning "offspring, progeny" rare now except in biblical use. Meaning "semen" is from c. 1300. For sporting sense, see seed (v.).
seed (v.): late 14c., "to flower, flourish; produce seed;" mid-15c., "to sow with seed," from seed (n.). Meaning "remove the seeds from" is from 1904. Sporting (originally tennis) sense (1898) is from notion of spreading certain players' names so as to ensure they will not meet early in a tournament. The noun in this sense is attested from 1924. Related: Seeded; seeding.
seed-cake (n.): 1570s, from seed (n.) + cake (n.).
seeded (adj.): 1922 in the sports sense (originally tennis), past participle adjective from seed (v.).
seedling (n.): "young plant developed from seed," 1650s, from seed (n.) + diminutive suffix -ling.
seedy (adj.): mid-15c., "fruitful, abundant," from seed (n.) + -y (2). From 1570s as "abounding in seeds." Meaning "shabby" is from 1739, probably in reference to the appearance of a flowering plant that has run to seed. Related: Seediness.
seeing (adj.): c. 1300, present participle adjective from see (v.). Seeing Eye dog first attested 1929, American English, trademarked by Seeing Eye Inc. of New Jersey.
seek (v.): Old English secan "inquire, search for; pursue; long for, wish for, desire; look for, expect from," influenced by Old Norse soekja, both from Proto-Germanic *sokjan (source also of Old Saxon sokian, Old Frisian seka, Middle Dutch soekan, Old High German suohhan, German suchen, Gothic sokjan), from PIE *sag-yo-, from root *sag- "to track down, seek out" (source also of Latin sagire "to perceive quickly or keenly," sagus "presaging, predicting," Old Irish saigim "seek"). The natural modern form of the Anglo-Saxon word as uninfluenced by Norse is in beseech. Related: Sought; seeking.
seeker (n.): early 14c., agent noun from seek. The religious sect of the Seekers is attested from 1645.
seem (v.): c. 1200, "to appear to be;" c. 1300, "to be fitting, be appropriate, be suitable," though the more recent sense in English is the etymological one; from Old Norse soema "to honor; to put up with; to conform to (the world, etc.)," verb derived from adjective soemr "fitting," from Proto-Germanic *somi- (source also of Old English som "agreement, reconciliation," seman "to conciliate," source of Middle English semen "to settle a dispute," literally "to make one;" Old Danish some "to be proper or seemly"), from PIE *som-i-, from root *sem- "one, as one" (see same). Related: Seemed; seeming.
seeming (adj.): late 14c., present participle adjective from seem. Seemingly in sense of "to all appearances" recorded from 1590s.
seemly (adj.): "of pleasing or good appearance," also "proper, tasteful, decorous," early 13c., semlich, from Old Norse soemiligr "becoming, honorable," from soemr (see seem). Related: Seemliness. Old Norse also had soemleitr "fine to look at."
seen: Middle English sein, from Old English gesegen, gesewen, past participle of seon (see see (n.)). From c. 1200 as "perceived, discovered." To have seen everything as a hyperbolic expression of astonishment is from 1941.
When you have seen one of their Pictures, you have seen all. [Blake, c. 1811]
seep (v.): 1790, variant of sipe (c. 1500), possibly from Old English sipian "to seep," from Proto-Germanic *sip- (source also of Middle High German sifen, Dutch sijpelen "to ooze"), from PIE root *seib- "to pour out, drip, trickle" (see soap (n.)). Related: Seeped; seeping.
seepage (n.): 1825, from seep + -age.
seer (n.): late 14c., "one to whom divine revelations are made," agent noun from see (v.). Originally rendering Latin videns, Greek bleptor (from Hebrew roeh) in Bible translations (such as I Kings ix:9). Literal sense of "one who sees" is attested from early 15c.
seersucker (n.): 1722, from Hindi sirsakar, East Indian corruption of Persian shir o shakkar "striped cloth," literally "milk and sugar," a reference to the alternately smooth and puckered surfaces of the stripes. From Persian shir (cognate with Sanskrit ksiram "milk") + shakar (cognate with Pali sakkhara, Sanskrit sarkara "gravel, grit, sugar;" see sugar (n.)).
seethe (v.): Old English seoþan "to boil," also figuratively, "be troubled in mind, brood" (class II strong verb; past tense seaþ, past participle soden), from Proto-Germanic *seuthan (source also of Old Norse sjoða, Old Frisian siatha, Dutch zieden, Old High German siodan, German sieden "to seethe"), from PIE root *seut- "to seethe, boil."

Driven out of its literal meaning by boil (v.); it survives largely in metaphoric extensions. Figurative use, of persons or populations, "to be in a state of inward agitation" is recorded from 1580s (implied in seething). It had wider figurative uses in Old English, such as "to try by fire, to afflict with cares." Now conjugated as a weak verb, and past participle sodden (q.v.) is no longer felt as connected.
seether (n.): late 14c., "one employed in boiling," agent noun from seethe.
segment (n.): 1560s, from Latin segmentum "a strip or piece cut off, a cutting, strips of colored cloth," from secare "to cut" (see section (n.)), with euphonious alteration of -c- to -g- before -m-. Latin segmentum was used in Medieval Latin as a geometry term, translating Greek tmema, and the word was first picked up in English in this sense. Meaning "segmental portion of anything circular" is from 1640s; general sense of "a division, section" is from 1762.
segment (v.): 1859, intransitive, in reference to cell division, from segment (n.). Transitive sense, "divide (something) into segments" is from 1872. Related: Segmented; segmenting.