Online Etymology Dictionary

glue-pot (n.): late 15c., from glue (n.) + pot (n.1).
gluey (adj.): late 14c., from glue (n.) + -y (2).
glug: 1768, imitative of the sound of swallowing a drink, etc.
glum (adj.): 1540s, "sullen, frowning," from Middle English gloumen (v.) "become dark" (c.1300), later gloumben "look gloomy or sullen" (late 14c.); see gloom. Related: Glumly; glumness.
glut (v.): early 14c., "to swallow too much; to feed to repletion," probably from Old French gloter "to swallow, gulp down," from Latin gluttire "swallow, gulp down," from PIE root *gwele- "to swallow" (cf. Russian glot "draught, gulp"). Related: Glutted; glutting.
glut (n.): 1530s, "a gulp," from glut (v.). Meaning "condition of being full or sated" is 1570s; mercantile sense is first recorded 1590s.
glutamate (n.): 1876, from glutamic acid (see gluten) + -ate (3).
gluteal (adj.): by 1804, from gluteus + -al (1).
gluten (n.): 1630s, "any sticky substance," from Middle French gluten (16c.) or directly from Latin gluten "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 (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.): "of the nature of glue," early 15c. (implied c.1400 in glutinosity), from Latin glutinosus "gluey, viscous, tenacious," from gluten (genitive glutinis) "glue" (see glue (n.)).
glutton (n.): early 13c., from Old French gluton (Modern French glouton), from Latin gluttonem (nominative glutto) "overeater," formed from gluttire "to swallow," from gula "throat," from PIE *gwele- (see glut (v.)).
gluttonous (adj.): mid-14c.; see glutton + -ous. Related: Gluttonously.
gluttony (n.): c.1200, glutunie, from Old French glutonie, from gluton "glutton" (see glutton). Gluttonry recorded from late 12c.
glycemic (adj.): 1923, from glycemia (also glycaemia), 1901, from glyco- + -emia.
glyceride (n.): compound of glycerol and organic acids; see glycerin + -ide.
glycerin (n.): also glycerine, thick, colorless syrup, 1838, from French glycérine, coined by French chemist Michel-Eugène Chevreul (1786-1889), from Greek glykeros "sweet" (see glucose) + 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.): 1884, from glycerine + -ol, suffix denoting alcohols.
glyco-: word-forming element meaning "sweet," from Latinized comb. form of Greek glykys "sweet" (see glucose). 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 glykys "sweet" (see glucose) + French -gène (see -gen). Coined in 1848 by French physiologist Claude Bernard (1813-1878).
glycogenic (adj.): 1859, from glycogen + -ic.
glycolysis (n.): 1892, from glyco- + -lysis.
glyph (n.): 1727, "ornamental groove in architecture," from French glyphe (1701), from Greek glyphe "a carving," from glyphein "to hollow out, cut out with a knife, engrave, carve," from PIE root *gleubh- "to cut, slice" (cf. Latin glubere "to peel, shell, strip," Old English cleofan "to cleave"). Meaning "sculpted mark or symbol" (as in hieroglyph) is from 1825.
glyptodon (n.): extinct gigantic mammal, 1838, irregularly formed from Greek glyptos "engraved" (verbal adjective of glyphein; see glyph) + odon (genitive odontos) "tooth" (see tooth).
gnarl (v.): "contort, twist," 1814, a back-formation from gnarled. As a noun from 1824. Earlier the verb was used in a sense of "to snarl" (1590s).
gnarled (adj.): the source of the group of words that includes gnarl (v.), gnarl (n.), gnarly is Shakespeare's use of gnarled in 1603:
Thy sharpe and sulpherous bolt Splits the vn-wedgable and gnarled Oke. ["Measure for Measure," II.ii.116]
OED and Barnhart call it a variant of knurled, from Middle English knar "knot in wood" (late 14c.), originally "a rock, a stone;" of uncertain origin. "(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.): 1829, "knotted and rugged," from gnarl (see gnarled) + -y (2). Picked up 1970s as surfer slang to describe a dangerous wave; it had spread in teen slang by 1982, where it meant both "excellent" and "disgusting."
gnash (v.): early 15c., variant of Middle English gnasten "to gnash the teeth" (c.1300), perhaps from Old Norse gnastan "a gnashing," of unknown origin, probably imitative. Cf. German knistern "to crackle." Related: Gnashed; gnashing.
gnat (n.): Old English gnætt "gnat, midge, mosquito," earlier gneat, used of various small, flying insects, from Proto-Germanic *gnattaz (cf. 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, transl. of Bartholomew de Glanville's "De proprietatibus rerum," 1398]
gnathic (adj.): "pertaining to the jaw," 1882, from Greek gnathos "jaw, cheek," properly "the lower jaw," cognate with Lithuanian žandas "jaw."
gnaw (v.): Old English gnagan (past tense *gnog, past participle gnagan) "to gnaw," a common Germanic word (cf. Old Saxon gnagan, Old Norse, Swedish gnaga, Middle Dutch, Dutch knagen, Old High German gnagan, German nagen "to gnaw"), probably imitative of gnawing. Related: Gnawed; gnawing.
gneiss (n.): 1757, from German Gneiss "type of metamorphic rock," probably from Middle High German gneist "spark" (so called because the rock glitters), from Old High German gneisto "spark" (cf. Old English gnast "spark," Old Norse gneisti).
gnocchi (n.): 1891, from Italian gnocchi, plural of gnocco, from nocchio "a knot in wood," perhaps from a Germanic source akin to knuckle. So called for their shape.
gnome (n.): "dwarf-like earth-dwelling spirit," 1712, from French gnome, from Modern Latin gnomus, used 16c. in a treatise by Paracelsus, who gave the name pigmaei or gnomi to elemental earth beings, possibly from Greek *genomos "earth-dweller" (cf. thalassonomos "inhabitant of the sea"). A less-likely suggestion is that Paracelsus based it on the homonym that means "intelligence" (preserved in gnomic). Popular in children's literature 19c. as a name for red-capped German and Swiss folklore dwarfs. Garden figurines first imported to England late 1860s from Germany.
gnomic (adj.): "full of instructive sayings," 1815, from French gnomique (18c.) and directly from Late Latin gnomicus "concerned with maxims, didactic," from Greek gnomikos, from gnome "thought, opinion, maxim, intelligence," from root of gignoskein "to come to know" (see gnostic). English gnome meant "short, pithy statement of general truth" (1570s). Gnomical is attested from 1610s.
gnomish (adj.): 1822, from gnome + -ish. Related: Gnomishly; gnomishness.
gnomist (n.): see gnomic + -ist.
gnomon (n.): "vertical shaft that tells time by the shadow it casts" (especially the triangular plate on a sundial), 1540s, from Latin gnomon, from Greek gnomon "indicator," literally "one who discerns," from gignoskein "to come to know" (see gnostic (adj.)).
gnosis (n.): "special knowledge of spiritual mysteries," 1703, from Greek gnosis "investigation, knowledge," in Christian writers, "higher knowledge of spiritual things" (see gnostic (adj.)).
Gnostic (n.): 1580s, "believer in a mystical religious doctrine of spiritual knowledge," from Late Latin Gnosticus, from Late Greek Gnostikos, noun use of adj. gnostikos "knowing, able to discern," from gnostos "knowable," from gignoskein "to learn, to come to know" (see know). Applied to various early Christian sects that claimed direct personal knowledge beyond the Gospel or the Church hierarchy.
gnostic (adj.): "relating to knowledge," 1650s, from Greek gnostikos "knowing, able to discern," from gnostos "known, perceived, understood," from gignoskein "to learn, to come to know" (see know).
Gnosticism (n.): 1660s, from Gnostic + -ism.
GNP (n.): abbreviation of gross national product, attested by 1953.
gnu (n.): 1777, gnoo, from Dutch gnoe, used by German traveler Georg Forster (1754-1794) to render Hottentot i-ngu "wildebeest," from Southern Bushman !nu: (in which ! and : represent clicks).
go (v.): Old English gan "to go, advance, depart; happen; conquer; observe," from West Germanic *gai-/*gæ- (cf. Old Saxon, Old Frisian gan, Middle Dutch gaen, Dutch gaan, Old High German gan, German gehen), from PIE *ghe- "to release, let go" (cf. Sanskrit jihite "goes away," Greek kikhano "I reach, meet with"), but there is not general agreement on cognates.

The Old English past tense was eode, of uncertain origin but evidently once a different word (perhaps connected to Gothic iddja); it was replaced 1400s by went, formerly past tense of wenden "to direct one's way" (see wend). In northern England and Scotland, however, eode tended to be replaced by gaed, a construction based on go. In modern English, only be and go take their past tenses from entirely different verbs.

The word in its various forms and combinations takes up 45 columns of close print in the OED. Verbal meaning "say" emerged 1960s in teen slang. Colloquial meaning "urinate or defecate" attested by 1926. Go for broke is from 1951, American English colloquial; go down on "perform oral sex on" is from 1916. That goes without saying (1878) translates French cela va sans dire. As an adjective, "in order," from 1951, originally in aerospace jargon.
go (n.): 1727, "action of going," from go (v.). The sense of "a try or turn at something" is from 1825; meaning "something that goes, a success" is from 1876. Phrase on the go "in constant motion" is from 1843.
go ahead: as a command to proceed, 1831. As an adjective phrase, by 1840.
go off (v.): of firearms, etc., 1570s; meaning "depart" is c.1600; that of "reprimand" is from 1941 (originally with at, since c.2000 more often with on).