glottochronology (n.)
1953, from glotto- + chronology.
Gloucester
English county, Old English Gleawceaster, from Latin Coloniae Glev (2c.), from Glevo, a Celtic name meaning "bright place" (perhaps influenced by Old English gleaw "wise, prudent") + Old English ceaster "Roman town" (see Chester). In reference to a type of cheese by 1802.
glove (n.)
Old English glof "glove, covering for the hand having separate sheaths for the fingers," also "palm of the hand," from Proto-Germanic *galofo "covering for the hand" (source also of Old Norse glofi), probably from *ga- collective prefix + *lofi "hand" (source also of Old Norse lofi, Middle English love, Gothic lofa "flat of the hand"), from PIE *lep- (2) "be flat; palm, sole, shoulder blade" (source also of Russian lopata "shovel;" Lithuanian lopa "claw," lopeta "shovel, spade").

German Handschuh, the usual word for "glove," literally "hand-shoe" (Old High German hantscuoh; also Danish and Swedish hantsche) is represented by Old English Handscio (the name of one of Beowulf's companions, eaten by Grendel), but this is attested only as a proper name. Meaning "boxing glove" is from 1847. Figurative use of fit like a glove is by 1771.
glove (v.)
"to cover or fit with a glove," c. 1400, from glove (n.). Related: Gloved; gloving. Old English had adjective glofed. Glover as a surname is from mid-13c.
glow (n.)
mid-15c., "glowing heat," from glow (v.). Meaning "a flush of radiant feeling" is from 1793.
glow (v.)
Old English glowan "to glow, shine as if red-hot," from Proto-Germanic *glo- (source also of Old Saxon gloian, Old Frisian gled "glow, blaze," Old Norse gloa, Old High German gluoen, German glühen "to glow, glitter, shine"), from PIE root *ghel- (2) "to shine," with derivatives referring to bright materials and gold. Figuratively from late 14c. Related: Glowed; glowing. Swedish dialectal and Danish glo also have the extended sense "stare, gaze upon," which is found in Middle English.
glow-worm (n.)
early 14c., from glow (v.) + worm (n.). Actually the wingless female form of a beetle (Lampyris noctiluca). The males have wings but do not glow.
glower (v.)
mid-14c., "to shine;" c. 1500, "to stare with wide eyes," perhaps from a Scandinavian source (compare Norwegian dialectal glora "to glow, gleam; stare"), or related to Middle Dutch gluren "to leer;" in either case from Proto-Germanic *glo- (see glow (v.)), root of Old English glowan "to glow," which influenced the spelling of this word. Meaning "to look angrily, look intently and threateningly, scowl" is from 18c. Related: Glowered; glowering. As a noun, 1715, "an angry or threatening stare," from the verb.
glucagon (n.)
1923, from gluco- + Greek agon, present participle of agein "push forward, put in motion; stir up; excite, urge," from PIE root *ag- "to drive, draw out or forth, move."
gluco-
before vowels, gluc-, word-forming element used since c. 1880s, a later form of glyco-, from Greek glykys "sweet," figuratively "delightful; dear; simple, silly," from *glku-, dissimilated in Greek from PIE root *dlk-u- "sweet" (source also of Latin dulcis). Now usually with reference to glucose.
glucose (n.)
name of a group of sugars (in commercial use, "sugar-syrup from starch"), 1840, from French glucose (1838), said to have been coined by French professor Eugène Melchior Péligot (1811-1890) from Greek gleukos "must, sweet wine," related to glykys "sweet" (see gluco-). It first was obtained from grape sugar. Related: Glucosic.
glue (n.)
"viscous adhesive substance," early 13c., from Old French glu "glue, birdlime" (12c.), from Vulgar Latin *glutis or Late Latin glutem (nominative glus) "glue," from Latin gluten "glue, beeswax," from PIE *gleit- "to glue, paste" (source also of Lithuanian glitus "sticky," glitas "mucus;" Old English cliða "plaster"), from root *glei- "clay," also forming words with a sense of "to stick together" (see clay). Formerly also glew. In reference to glue from boiled animal hoofs and hides, c. 1400. Glue-sniffing attested from 1963.
glue (v.)
"join or fasten with glue," late 14c., from Old French gluer, gluier "smear with glue; join together," from glu "glue, birdlime" (see glue (n.)). Related: Glued; gluing.
glue-pot (n.)
late 15c., from glue (n.) + pot (n.1). Typically a double pot, one within the other, the inner one for the glue, the outer for the hot water.
gluey (adj.)
late 14c., from glue (n.) + -y (2).
glug (n.)
1768, imitative of the sound of swallowing a drink, etc. From 1895 as a verb. Compare Middle English glub "to swallow greedily."
glum (adj.)
1540s, "sullen, moody, frowning," from Middle English gloumen (v.) "become dark" (c. 1300), later gloumben "look gloomy or sullen" (late 14c.); see gloom. Or from or influenced by Low German glum "gloomy, troubled, turbid." In English the word was also formerly a noun meaning "a sullen look" (1520s). An 18c. extended or colloquial form glump led to the expression the glumps "a fit of sulkiness." Glunch (1719) was a Scottish variant. Related: Glumly; glumness.
glut (v.)
early 14c., glotien "to feed to repletion" (transitive), probably from Old French glotir "to swallow, gulp down, engulf," from Latin glutire/gluttire "to swallow, gulp down," from PIE root *gwele- (3) "to swallow" (see gullet). Intransitive sense "feed (oneself) to repletion" is from c. 1400. Related: Glutted; glutting.
glut (n.)
1530s, "a gulp, a swallowing," from glut (v.). Meaning "condition of being full or sated" is 1570s; mercantile sense "superabundance, oversupply of a commodity on the market" first recorded 1590s.
glutamate (n.)
salt of glutamic acid, 1876, from glutamic acid (see gluten) + -ate (3).
gluteal (adj.)
also glutaeal, by 1804, from gluteus + -al (1).
gluten (n.)
1630s, "a sticky substance," from Middle French gluten "sticky substance" (16c.) or directly from Latin gluten (glutin-) "glue" (see glue (n.)). Used 16c.-19c. for the part of animal tissue now called fibrin; used since 1803 of the nitrogenous part of the flour of wheat or other grain; hence glutamic acid (1871), a common amino acid, and its salt, glutamate.
gluteus (n.)
buttocks muscle, 1680s, from Modern Latin glutaeus, from Greek gloutos "the rump," in plural, "the buttocks."
glutin (n.)
1825, from French glutine, probably from Latin gluten "glue" (see gluten) + chemical suffix -ine (2). Used in chemistry in several senses before settling on "gelatin prepared from animal hides, hoofs, etc." (1845).
glutinous (adj.)
"viscous, sticky, of the nature of glue," early 15c., from Latin glutinosus "gluey, viscous, tenacious," from gluten (genitive glutinis) "glue" (see glue (n.)). Glutinosity is from c. 1400. Related: Glutinousness.
glutton (n.)
"one who eats and drinks to excess," early 13c., from Old French gloton "glutton;" also "scoundrel," a general term of abuse (Modern French glouton), from Latin gluttonem (nominative glutto) "overeater," formed from gluttire "to swallow," from gula "throat," from PIE *gwele- (3) "to swallow" (see gullet). General sense in reference to one who indulges in anything to excess is from 1704. Glutton for punishment is from pugilism; the phrase is from 1854, but the idea is older:
Thus, Theocritus, in his Milling-match, calls Amycus "a glutton," which is well known to be the classical phrase at Moulsey-Hurst, for one who, like Amycus, takes a deal of punishment before he is satisfied. [Tom Moore, "Tom Crib's Memorial to Congress," 1819]
gluttonous (adj.)
mid-14c.; see glutton + -ous. Related: Gluttonously.
gluttony (n.)
"extravagant indulgence of appetite," c. 1200, glutunie, from Old French glotonie "debauchery, gluttony," from gloton "glutton" (see glutton). Gluttonry recorded from late 12c.
glycemia (n.)
also glycaemia, "presence or level of sugar in the blood," 1901, from glyco- "sugar" + -emia "condition of the blood."
glycemic (adj.)
1923, from glycemia + -ic.
glyceride (n.)
compound of glycerol and organic acids, 1864; see glycerin + -ide.
glycerin (n.)
also glycerine, thick, colorless syrup, 1838, from French glycérine, coined by French chemist Michel-Eugène Chevreul (1786-1889), from glycero- "sweet" + chemical ending -ine (2). So called for its sweet taste. Still in popular use, but in chemistry the substance now is known as glycerol.
glycerine (n.)
see glycerin.
glycerol (n.)
1872, from glycerine + -ol, suffix denoting alcohols.
glyco-
before vowels glyc-, word-forming element meaning "sweet," from Latinized comb. form of Greek glykys, glykeros "sweet" (see gluco-). Used in reference to sugars generally. OED says a regular formation would be glycy-.
glycogen (n.)
starch-like substance found in the liver and animal tissue, 1860, from French glycogène, "sugar-producer," from Greek-derived glyco- "sweet" (see glyco-) + French -gène (see -gen). Coined in 1848 by French physiologist Claude Bernard (1813-1878).
glycogenic (adj.)
1856, from French; see glycogen + -ic.
glycolysis (n.)
1891, from French; see glyco- + -lysis.
glyph (n.)
1727, "ornamental groove in sculpture or architecture," from French glyphe (1701), from Greek glyphe "a carving," from glyphein "to hollow out, cut out with a knife, engrave, carve," also "to note down" on tablets, from PIE root *gleubh- "to cut, slice, tear apart" (source also of Latin glubere "to peel, shell, strip," Old English cleofan "to cleave," Old Norse klofi, Middle Dutch clove "a cleft"). Meaning "sculpted mark or symbol" (as in hieroglyph) is from 1825. Related: Glyphic.
glyptodon (n.)
extinct gigantic armadillo-like mammal from the Pleistocene of South America, 1838, irregularly formed from Greek glyptos "carved, engraved" (verbal adjective of glyphein; see glyph) + odon (genitive odontos) "tooth" (from PIE root *dent- "tooth"). So named for its fluted teeth.
gn-
consonant cluster at the head of some words; the -g- formerly was pronounced. Found in words from Old English (gnat, gnaw), in Low German, and Scandinavian as a variant of kn- (gneiss), in Latin and Greek (gnomon, gnostic) and representing sounds in non-Indo-European languages (gnu).
gnarl (v.)
"contort, twist, make knotty," 1814, a back-formation from gnarled (q.v.). As a noun from 1824, "a knotty growth on wood." Earlier an identical verb was used imitatively in a sense of "to snarl" like a dog (1590s); Farmer & Henley lists gnarler as thieves' slang for "a watch-dog."
gnarled (adj.)
c. 1600, probably a variant of knurled, from Middle English knar "knob, knot in wood, protruding mass on a tree" (late 14c.), earlier "a crag, rugged rock or stone" (early 13c.), from a general group of Germanic words that includes English knob, knock, knuckle, knoll, knurl. Gnarl (v.) "make knotty," gnarl (n.) "a knotty growth on wood," and gnarly (adj.) all seem to owe their existence in modern English to Shakespeare's use of gnarled in 1603:
[T]hy sharpe and sulpherous bolt Splits the vn-wedgable and gnarled Oke. ["Measure for Measure," II.ii.116]
"(Gnarled) occurs in one passage of Shakes. (for which the sole authority is the folio of 1623), whence it came into general use in the nineteenth century" [OED].
gnarly (adj.)
"knotted and rugged," c. 1600, from gnarl (see gnarled) + -y (2). Picked up 1970s as surfer slang to describe a dangerous wave; it had spread to teen slang by 1982, where it meant both "excellent" and "disgusting."
gnash (v.)
early 15c. variant of Middle English gnasten "to grind the teeth together" in rage, sorrow, or menace (early 14c.), perhaps from Old Norse gnasta, gnista "to gnash the teeth," of unknown origin, probably imitative. Compare German knistern "to crackle," Old English gnidan "to rub, bruise, pound, break to pieces," Danish knaske "crush with the teeth." Related: Gnashed; gnashing.
gnat (n.)
Old English gnæt "gnat, midge, small flying insect," earlier gneat, from Proto-Germanic *gnattaz (source also of Low German gnatte, German Gnitze); perhaps literally "biting insect" and related to gnaw.
The gnatte is a litil fflye, and hatte culex he soukeþ blood and haþ in his mouþ a pipe, as hit were a pricke. And is a-countid a-mong volatiles and greueþ slepinge men wiþ noyse & wiþ bytinge and wakeþ hem of here reste. [John of Trevisa, translation of Bartholomew de Glanville's "De proprietatibus rerum," 1398]
Gnat-catcher, insectivorous bird of the U.S. woodlands, is from 1823.
gnathic (adj.)
"pertaining to the jaw," 1882, with -ic + Greek gnathos "jaw, cheek," properly "the lower jaw," from PIE root *genu- (2) "jawbone, chin."
gnatho-
before vowels gnath-, word-forming element meaning "jaw, mouth part, beak (of a bird)," from Greek gnathos "jaw," from PIE root *genu- (2) "jawbone, chin."
gnaw (v.)
Old English gnagan "to gnaw, bite off little by little" (past tense *gnog, past participle gnagan), from Proto-Germanic *gh(e)n- "to gnaw" (source also of Old Saxon gnagan, Old Norse, Swedish gnaga, Middle Dutch, Dutch knagen, Old High German gnagan, German nagen "to gnaw"), probably imitative of gnawing. Figurative sense "wear away as if by continued biting" is from early 13c. Related: Gnawed; gnawing.
gneiss (n.)
type of metamorphic rock, 1757, kneiss, from German Gneiss (16c.), which is probably from Middle High German gneist "spark" (so called because the rock glitters), from Old High German gneisto "spark" (compare Old English gnast "spark," Old Norse gneisti). Related: Gneissic.