- X
- most Eng. words beginning in -x- are of Gk. origin or modern commercial coinages. E. 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 Eng.), sometimes said to be from medieval use, originally a crossed -r-, probably from L. radix (see root). 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 used 1950 in Britain to designate "films deemed suitable for adults only;" adopted in U.S. Nov. 1, 1968.
- X-ray
- 1896, translation of Ger. X-strahl, from X, algebraic symbol for an unknown quantity, + Strahl (pl. Strahlen) "beam, ray." Coined 1895 by Ger. scientist Wilhelm Conrad Röntgen (1845-1923), who discovered them.
- Xanadu
- Mongol city founded by Kublai Khan, 1625, Anglicized form of Shang-tu. Sense of "dream place of magnificence and luxury" derives from Coleridge's poem (1816).
- Xanthippe
- 1596, 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" + hippos "horse."
- xanthous
- 1829, from Gk. 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
- "small three-masted vessel," 1756, from Fr. chébec, from It. sciabecco, ult. from Ar. shabbak "a small warship." Altered by infl. of cognate Sp. xabeque, which shows the old way of representing the Sp. sound now spelled -j-.
- Xenia
- city in Ohio, from Gk. xenia "hospitality," lit. "state of a guest," from xenos "guest," of unknown origin, perhaps cognate with L. hostis "stranger, enemy." Founded 1803 and named by vote of a town meeting, on suggestion of the Rev. Robert Armstrong to suggest freindliness and hospitality.
- xenon
- 1898, from Gk. neut. of xenos "foreign, strange," coined by its discoverer, Scottish chemist Sir William Ramsay (1852-1916); cf. krypton.
- xenophobic
- 1912, coined from Gk. xenos "foreign, stranger" + phobos "fear" (see phobia).
- xerasia
- 1706, "excessive dryness of hair," Medical L., from Gk. xerasia "dryness," from xeros "dry."
- Xeres
- 1661, name of Andalusian town (modern Jerez) famous for its wine (see sherry). For first letter, see xebec.
- 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 Gk. xeros "dry" + -ography as in photography. The verb is first attested 1965, from the noun, despite strenuous objection from the Xerox copyright department.
- Xerxes
- king of Persia who reigned 486-465 B.C.E., Gk. Xerxes, from O.Pers. Xšayaršan, lit. "male (i.e. 'hero') among kings," from Xšaya- "king" (cf. shah) + aršan "male, man." The Heb. rendition was Ahashwerosh, Ahashresh.
- xiphias
- 1667, genus of swordfish, from Gk. xiphias "swordfish," from xiphos "sword," of unknown origin.
- Xmas
- "Christmas," 1551, X'temmas, wherein the X is an abbreviation for Christ in Christmas, from first letter of Gk. 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
- "woody tissue in higher plants," 1875, from Ger. Xylem, coined from Gk. xylon "wood," of unknown origin.
- xylophone
- 1866, coined from Gk. xylon "wood" + phone "a sound" (see fame).
- xyster
- "surgical instrument for scraping bones," 1684, from Gk. xyster, from xyein "to scrape," from PIE base *kes- "to scrape."