Online Etymology Dictionary

segmental (adj.): 1816, from segment (n.) + -al (1).
segmentation (n.): 1650s, "a cutting in small pieces;" 1851 of cells, from segment (v.) + -ation.
segregate (v.): 1540s, from Latin segregatus, past participle of segregare "set apart, lay aside; isolate; divide," literally "separate from the flock," from *se gregare, from se "apart from" (see secret (n.)) + grege, ablative of grex "herd, flock" (see gregarious). Originally often with reference to the religious notion of separating the flock of the godly from sinners. In modern social context, "to force or enforce racial separation and exclusion," 1908. Related: Segregated; segregating.
segregation (n.): 1550s, "act of segregating," from Late Latin segregationem (nominative segregatio), noun of action from past participle stem of segregare (see segregate). Meaning "state of being segregated" is from 1660s. Specific U.S. sense of "enforced separation of races" is attested from 1883.
Rarely are we met with a challenge, not to our growth or abundance, or our welfare or our security, but rather to the values and the purposes and the meaning of our beloved nation. The issue of equal rights for American Negroes is such an issue. And should we defeat every enemy, and should we double our wealth and conquer the stars, and still be unequal to this issue, then we will have failed as a people and as a nation. [Lyndon Johnson, speech introducing Voting Rights Act, March 15, 1965]
segregationist (n.): 1915, from segregation + -ist.
segue (n.): 1740, an instruction in musical scores, from Italian segue, literally "now follows," meaning to play into the following movement without a break, third person singular of seguire "to follow," from Latin sequi "to follow," from PIE *sekw- (1) "to follow" (see sequel). Extended noun sense of "transition without a break" is from 1937; the verb in this sense is first recorded 1958.
Segway: trademark name (Segway Inc., Bedford, New Hampshire, U.S.), in use from 2001; according to the company, chosen for similarity to segue on notion of "a smooth transition from one place to another," with probably influence of way (n.).
seigneur (n.): "feudal landowner in France," 1590s, from Middle French seigneur, from Old French seignor (see seignior). Related: Seigneuress.
seignior (n.): "lord of a manor," late 13c., from Old French seignior (11c., Modern French seigneur), from Latin seniorem (nominative senior) "older" (see senior (adj.)). As a general title for a Frenchman, it dates from 1580s. Related: Seigniorial; seignioral.
seigniorage (n.): mid-15c., from Old French seignorage, from seignor (see seignior).
seine (n.): Old English segne "drag-net," from West Germanic *sagina (source also of Old Saxon and Old High German segina), a borrowing of Latin sagena (source also of French seine, 12c., which contributed to the form of the English word), from Greek sagene "a fishing net," also "a hunting net," a word of unknown origin.
seismic (adj.): 1858, from seismo- + -ic.
seismo-: word-forming element meaning "earthquake," from comb. form of Greek seismos "a shaking, shock; an earthquake," from seiein "to shake," from PIE root *twei- "to agitate, shake, toss."
seismogram (n.): record made by a seismograph or seismometer, 1888, from seismo- + -gram.
seismograph (n.): "instrument for measuring the motions of an earthquake," 1858, from seismo- + -graph. Based on Italian sismografo, coined and invented by Luigi Palmieri (1807-1896), director of meteorological observation on Mount Vesuvius. Related: Seismographic; seismography (1865).
seismologist (n.): 1859, from seismology + -ist.
seismology (n.): 1852, from seismo- + -logy. Related: Seismological (1850).
seismometer (n.): "instrument for measuring the intensity and motion of earthquakes," 1841, from seismo- + -meter. Originally different from a seismograph but now practically the same thing.
seize (v.): mid-13c., from Old French seisir "to take possession of, take by force; put in possession of, bestow upon" (Modern French saisir), from Late Latin sacire, which is generally held to be from a Germanic source, but the exact origin is uncertain. Perhaps from Frankish *sakjan "lay claim to" (compare Gothic sokjan, Old English secan "to seek;" see seek). Or perhaps from Proto-Germanic *satjan "to place" (see set (v.)).

Originally a legal term in reference to feudal property holdings or offices. Meaning "to grip with the hands or teeth" is from c. 1300; that of "to take possession by force or capture" (of a city, etc.) is from mid-14c. Figurative use, with reference to death, disease, fear, etc. is from late 14c. Meaning "to grasp with the mind" is attested from 1855. Of engines or other mechanisms, attested from 1878. Related: Seized; seizing.
seizure (n.): "act of seizing," late 15c., from seize + -ure. Meaning "sudden attack of illness" is attested from 1779.
sejm (n.): congress of the Polish republic, 1690s, from Polish sejm "assembly," from *syn-imu, literally "a taking together," from *syn- "together" (see syn-) + PIE root *em- "to take" (see exempt).
selah: 1520s, Hebrew word occurring frequently at the end of verse in Psalter. Supposed to be a liturgical direction, perhaps meaning "pause," or perhaps a musical direction to raise the voice (compare Hebrew base s-l-l "to raise, lift").
seldom (adv.): late Old English seldum, alteration of seldan "seldom, rarely," from Proto-Germanic *selda- "strange, rare" (source also of Old Norse sjaldan, Old Frisian selden, Dutch zelden, Old High German seltan, German selten), perhaps ultimately from the base of self (q.v.).

Form shifted on analogy of adverbial dative plurals in -um (such as whilom "at one time," from while). The same development also created litlum from little, miclum from mickle. German seltsam "strange, odd," Dutch zeldzaam are related, but with the second element conformed to their versions of -some.

Seldom-times is from mid-15c. (Old English had seldhwanne "seldwhen"). Seldom-seen is from mid-15c. (Old English had seldsiene, "seld-seen").

Some compounds using the old form survived through Middle English, such as selcouth"rarely or little-known, unusual, strange, wonderful," from Old English selcuð, seld-cuð, from seldan + cuð (see couth). Old English seldan had comparative seldor, superlative seldost; in early Middle English, as seldan changed form and lost its connection with these, selde was formed as a positive. Shakespeare uses seld-shown.
select (adj.): 1560s, from Latin selectus, past participle of seligere "choose out, single out, select; separate, cull," from se- "apart" (see secret (n.)) + legere "to gather, select" (see lecture (n.)). The noun meaning "a selected person or thing, that which is choice" is recorded from c. 1600. New England selectman first recorded 1640s.
select (v.): "to single out one or more out of a number of things of the same kind," 1560s, from select (adj.) or from Latin selectus. Related: Selected; selecting.
selection (n.): 1620s, "act of selecting," from Latin selectionem (nominative selectio) "a choosing out, choice, selection," noun of action from past participle stem of seligere (see select (adj.)). Meaning "thing selected" is from 1805. Biological sense is from 1837; applied to actions of breeders (methodical selection), hence its use by Darwin (natural selection; 1857). French sélection is a 19c. borrowing from English.
selective (adj.): 1620s; see select (adj.) + -ive. Related: Selectively; selectiveness. Selective service is from 1917, American English.
Selene: moon goddess, equivalent of Latin Luna, from Greek selene "the moon; name of the moon goddess," related to selas "light, brightness, bright flame, flash of an eye," from PIE root *swel- (2) "to shine, beam" (source also of Sanskrit svargah "heaven," Lithuanian svilti "to singe," Old English swelan "to be burnt up," Middle Low German swelan "to smolder"); related to swelter, sultry. Related: Selenian "of or pertaining to the moon as a world," 1660s.
selenium (n.): element name, Modern Latin, from Greek selene "moon" (see Selene). Named by Berzelius (1818), on analogy of tellurium, with which it had been at first confused, and which was named for the earth. Despite the -ium ending it is not a metal and a more appropriate name selenion has been proposed.
selenographer (n.): "student of the moon," 1660s, from selenography (1640s), from comb. form of Selene + -graphy.
Seleucid: 1803, in reference to dynasty founded in Syria 312 B.C.E. by Seleucus Nicator, general of Alexander. It lasted until the Roman conquest 65 B.C.E. The Seleucidan Era, a local reckoning in the East (maintained by Syrian Christians) usually is dated to Sept. 1, 312 B.C.E.
self (pron.): Old English self, seolf, sylf "one's own person, -self; own, same," from Proto-Germanic *selbaz (source also of Old Norse sjalfr, Old Frisian self, Dutch zelf, Old High German selb, German selb, selbst, Gothic silba), Proto-Germanic *selbaz "self," from PIE *sel-bho-, suffixed form of root *s(w)e-, pronoun of the third person and reflexive (referring back to the subject of a sentence), also used in forms denoting the speaker's social group, "(we our-)selves" (see idiom).
Trying to define yourself is like trying to bite your own teeth. [Alan Watts]
Its use in compounds to form reflexive pronouns grew out of independent use in Old English. As a noun from early 14c.
self-: word forming element indicating "oneself," also "automatic," from Old English use of self (pron.) in compounds, such as selfbana "suicide," selflice "self-love, pride, vanity, egotism," selfwill "free will."
self-absorbed (adj.): 1796, from self- + absorbed (see absorb).
self-abuse (n.): c. 1600, "self-deception," from self- + abuse (n.). As a synonym for "masturbation," it is recorded from 1728; an earlier term was self-pollution (1620s).
self-actualization (n.): 1939, from self- + actualization. Popularized, though not coined, by U.S. psychologist and philosopher Abraham H. Maslow (1908-1970).
self-aggrandizing (adj.): 1798, from self- + aggrandizing (see aggrandize).
self-appointed (adj.): 1750, from self- + appointed.
self-assertive (adj.): 1853, from self- + assertive. Related: Self-assertively; self-assertiveness.
self-assurance (n.): 1590s, from self- + assurance.
self-assured (adj.): 1711, from self- + assured.
self-aware (adj.): 1892, from self- + aware.
self-awareness (n.): 1876, from self- + awareness.
self-centered (adj.): 1670s, "fixed, stationary," from self- + center (v.). In reference to persons, "engrossed in the self, with little regard for others," it is recorded from 1783.
self-complacency (n.): 1680s, from self- + complacency.
self-complacent (adj.): 1760, back-formation from self-complacency or else from self- + complacent. Related: Self-complacently.
self-concept (n.): also self concept, 1921, from self- + concept.
self-confidence (n.): also self confidence, 1650s, from self- + confidence.
self-confident (adj.): 1610s, from self- + confident. Related: self-confidently.
self-congratulation (n.): 1630s, from self- + congratulation.