- X
- most English words beginning in -x- are of Greek origin or modern commercial coinages. East Anglian in 14c. showed a tendency to use -x- for initial sh-, sch- (cf. xal for shall), which didn't catch on but seems an improvement over the current system. As a symbol of a kiss on a letter, etc., it is recorded from 1765. In malt liquor, XX denoted "double quality" and XXX "strongest quality" (1827).
Algebraic meaning "unknown quantity" (1660 in English), sometimes said to be from medieval use, originally a crossed -r-, probably from Latin radix (see root (n.)). Other theories trace it to Arabic, but a more prosaic explanation says Descartes (1637) took x, y, z, the last three letters of the alphabet, for unknowns to correspond to a, b, c, used for known quantities.
Used allusively for "unknown person" from 1797, "something unknown" since 1859. As a type of chromosome, attested from 1902 (first so called in German; Henking, 1891). First used 1950 in Britain to designate "films deemed suitable for adults only;" adopted in U.S. Nov. 1, 1968. - X-ray (n.)
- 1896, translation of German X-strahl, from X, algebraic symbol for an unknown quantity, + Strahl (plural Strahlen) "beam, ray." Coined 1895 by German scientist Wilhelm Conrad Röntgen (1845-1923), who discovered them.
- Xanadu
- Mongol city founded by Kublai Khan, 1620s, anglicized form of Shang-tu. Sense of "dream place of magnificence and luxury" derives from Coleridge's poem (1816).
- xanthic (adj.)
- 1817, from French xanthique, from Greek xanthos "yellow" (see xanthous).
- Xanthippe
- late 16c., spouse of Socrates (5c. B.C.E.), the prototype of the quarrelsome, nagging wife. The name is related to the masc. proper name Xanthippos, a compound of xanthos "yellow" (see xanthous) + hippos "horse" (see equine).
- xanthosis (n.)
- 1857, Modern Latin, from Greek xanthos (see xanthous) + -osis.
- xanthous (adj.)
- 1829, from Greek xanthos "yellow," of unknown origin. Prefix form xantho- is used in many scientific words; cf. xanthein (1857) "soluble yellow coloring matter in flowers," Huxley's Xanthochroi (1867) "blond, light-skinned races of Europe" (with okhros "pale"), xanthophyll (1838) "yellow coloring matter in autumn leaves."
- xebec (n.)
- "small three-masted vessel," by 1745, from French chébec, from Italian sciabecco, ultimately from Arabic shabbak "a small warship." Altered by influence of cognate Spanish xabeque, which shows the old way of representing the Spanish sound now spelled -j-.
- Xenia
- city in Ohio, from Greek xenia "hospitality," literally "state of a guest," from xenos "guest" (see guest). Founded 1803 and named by vote of a town meeting, on suggestion of the Rev. Robert Armstrong to suggest friendliness and hospitality.
- xeno-
- before vowels, xen-, word-forming element meaning "strange, foreign; stranger, foreigner," from Greek xeno-, comb. form of xenos "a guest, stranger, foreigner" (see guest (n.)).
- xenolith (n.)
- 1894, from xeno- "foreign, strange" + -lith "stone."
- xenon (n.)
- gaseous element, 1898, from Greek xenon, neuter of xenos "foreign, strange" (see guest); coined by its co-discoverer, Scottish chemist Sir William Ramsay (1852-1916); cf. krypton.
- xenophile (nj.)
- 1922, from xeno- "foreign, strange" + -phile.
- xenophilic (adj.)
- 1974, from xenophile + -ic.
- xenophobe (n.)
- 1897, from xeno- "foreign, strange" + -phobe. As an adjective from 1908.
- xenophobia (n.)
- 1903, from xeno- "foreign, strange" + -phobia "fear." Earlier (c.1884) it meant "agoraphobia."
- xenophobic (adj.)
- 1912, from xenophobia + -ic.
- xerasia (n.)
- "excessive dryness of hair," 1706, medical Latin, from Greek xerasia "dryness," from xeros "dry," from PIE *ksero- "dry."
- Xeres
- Andalusian town (modern Jerez) famous for its wine; see sherry. For first letter, see xebec.
- xeric (adj.)
- 1926; see xero- + -ic.
- xero-
- before vowels, xer-, word-forming element meaning "dry," from Greek xero-, comb. form of xeros "dry" (see xerasia).
- xerophyte (n.)
- 1906, from xero- + Greek phyton "a plant" (see phyto-).
- xerotic (adj.)
- 1901, from xerosis (1890), Modern Latin, from Greek xerosis, from xeros "dry" (see xerasia) + -osis.
- Xerox
- 1952, trademark taken out by Haloid Co. of Rochester, N.Y., for a copying device, from earlier xerography "photographic reduplication without liquid developers" (1948), from Greek xeros "dry" (see xerasia) + -ography as in photography. The verb is first attested 1965, from the noun, despite strenuous objection from the Xerox copyright department. Related: Xeroxed; Xeroxing.
- Xerxes
- king of Persia who reigned 486-465 B.C.E., Greek Xerxes, from Old Persian Xšayaršan, literally "male (i.e. 'hero') among kings," from Xšaya- "to rule over" (cf. shah) + aršan "male, man, hero." The Hebrew rendition was Ahashwerosh, Ahashresh.
- xi (n.)
- fourteenth letter of the Greek alphabet.
- xiphias (n.)
- 1660s, genus of swordfish, from Greek xiphias "swordfish," from xiphos "sword," of unknown origin.
- xiphoid (adj.)
- 1851, from xiphias "swordfish" + -oid.
- Xmas (n.)
- "Christmas," 1551, X'temmas, wherein the X is an abbreviation for Christ in Christmas, from first letter of Greek Christos "Christ" (see Christ). The earlier way to abbreviate it was Xp- or Xr-, corresponding to "Chr-," and the form Xres mæsse for "Christmas" appears in the "Anglo-Saxon Chronicle" (c.1100).
- xylem (n.)
- "woody tissue in higher plants," 1875, from German Xylem, coined from Greek xylon "wood," of unknown origin.
- xylene (n.)
- 1851, from Greek xylon "wood," which is of unknown origin, + -ene.
- xylophone (n.)
- 1866, coined from Greek xylon "wood" + phone "a sound" (see fame (n.)).
- xyster (n.)
- "surgical instrument for scraping bones," 1680s, from Greek xyster, from xyein "to scrape," from PIE root *kes- "to scrape."