Online Etymology Dictionary

hexane (n.): paraffin hydrocarbon, 1872, from Greek hex "six" (see six) + chemical suffix -ane. So called for its six carbon atoms.
hexapod: 1660s (n.); 1856 (adj.), from Greek hex "six" (see six) + pod, from Greek pod-, stem of pous "foot" (see foot).
hey: c.1200, variously, in Middle English, hei, hai, ai, he, heh, expressing challenge, rebuttal, anger, derision, sorrow, or concern; also a shout of encouragement to hunting dogs. Possibly a natural expression (cf. Roman eho, Greek eia, German hei).
Þa onswerede þe an swiðe prudeliche, `Hei! hwuch wis read of se icudd keiser!' ["St. Katherine of Alexandria," c.1200]
In Latin, hei was a cry of grief or fear; but heia, eia was an interjection denoting joy.
heyday (n.): late 16c., alteration of heyda (1520s), exclamation of playfulness or surprise, something like Modern English hurrah, apparently an extended form of Middle Elish interjection hey or hei (see hey). Modern sense of "stage of greatest vigor" first recorded 1751, which altered the spelling on model of day, with which this word apparently has no etymological connection.
Hezbollah (n.): extremist Shiite group active in Lebanon, founded c.1982, from Persian hezbollah, Arabic hizbullah, literally "Party of God," from hezb/hizb "party" + allah "God." An adherent is a Hezbollahi. The name of various Islamic groups in modern times, the name itself is attested in English by 1960 in referense to an Indonesian guerilla battalion of 1945 that "grew out of a similarly named organization formed by the Japanese to give training in military drill to young Moslems."
In Modjokuto (like Masjumi itself, Hizbullah was Indonesia-wide but, also like Masjumi, it had little effective central organization) this group was led by the present head of Muhammadijah -- the same man who a year or so before was going to Djakarta for propaganda training and studying to be a kamikaze. [Clifford Geertz, "The Religion of Java," Chicago, 1960]
Hezekiah: masc. proper name, biblical, from Hebrew Hizqiyya, literally "the Lord has strengthened," from hazaq "he was strong, he strengthened" + jah, short for yahweh.
hi: greeting, 1862, American English (first recorded reference is to speech of a Kansas Indian), originally to attract attention (15c.), probably a variant of Middle English hy, hey (late 15c.) also an exclamation to call attention. Extended form hiya attested from 1940.
hi-fi (adj.): 1947, abbreviation of high fidelity (1934), of radio recievers, in reference to their quality of sound reproduction. Hi as an advertiser's phonetic shortening of high is attested by 1914.
hiatal (adj.): 1906, from stem of hiatus + -al (1).
hiatus (n.): 1560s, "break or opening in a material object," from Latin hiatus "opening, aperture, rupture, gap," from past participle stem of hiare "to gape, stand open" (see yawn (v.)). Sense of "gap or interruption in events, etc." is first recorded 1610s.
hibachi (n.): 1863, from Japanese hibachi "firepot," from hi "fire" + bachi, hachi "bowl, pot," which Watkins derives ultimately from Sanskrit patram "cup, bowl."
hibernacle (n.): "winter residence," 1708, from Latin hibernaculum "winter residence, winter quarters," related to hibernare "to winter" (see hibernation) with instrumentive suffix -culum. Related: Hibernacular.
hibernal (adj.): 1620s, from Latin hibernalis "wintry," from hibernus "of winter," from hiems "winter" (see hibernation).
hibernate (v.): 1802, probably a back-formation from hibernation. Related: Hibernated; hibernating.
hibernation (n.): 1660s, from Latin hibernationem (nominative hibernatio) "the action of passing the winter," noun of action from past participle stem of hibernare "to winter, pass the winter, occupy winter quarters;" related to hiems "winter," from PIE *gheim- "snow, winter" (cf. Sanskrit heman "in winter," Hittite gimmanza, Greek kheima, Old Church Slavonic zima, Lithuanian žiema "winter").
Hibernia: Roman name for Ireland, from Old Celtic *Iveriu "Ireland" (see Irish). Form altered in Latin as though it meant "land of winter" (see hibernation).
Hibernian: 1630s (adj.), 1709 (n.); see Hibernia + -ian. Related: Hibernianism.
hibiscus (n.): 1706, from Latin hibiscum, later hibiscus, "marshmallow plant," of unknown origin, perhaps from Gaulish.
hic: imitation of the sound of hiccuping, attested by 1883 (see hiccup).
hic et nunc: Latin, literally "here and now," from demonstrative pronomial adjective of place hic "here" + nunc (see now).
hic jacet: Latin, hic iacet, "here lies," commonly the first words of Latin epitaphs; from demonstrative pronomial adjective of place hic "here" + iacet "it lies," from iacere "to lie, rest," related to iacere "to throw" (see jet (v.)).
hiccough: 1620s, variant of hiccup (q.v.) by mistaken association with cough.
hiccup (n.): 1570s, hickop, earlier hicket, hyckock, "a word meant to imitate the sound produced by the convulsion of the diaphragm" [Abram Smythe Farmer, "Folk-Etymology," London, 1882]. Cf. French hoquet, Danish hikke, etc. Modern spelling first recorded 1788; An Old English word for it was ælfsogoða, so called because hiccups were thought to be caused by elves.
hiccup (v.): 1580s; see hiccup (n.).
hiccups (n.): a bout of hiccupping, by 1723; see hiccup (n.). This often also was called hiccup or the hiccup.
hick (n.): late 14c. as a pet form of masc. proper name Richard. Meaning "awkward provincial person" was established by 1700 (cf. rube); earlier it was the characteristic name of a hosteler, hackneyman, etc. (late 14c.), perhaps via alliteration. The adjective is recorded by 1914.
A hick town is one where there is no place to go where you shouldn't be. [attributed to U.S. humorist Robert Quillen (1887-1948)]
hickey (n.): see hickie.
hickie (n.): "love bite; mark on skin made by biting or sucking during foreplay or sex," 1934; earlier "pimple, skin lesion" (c.1915); perhaps a sense extension and spelling variation from earlier word meaning "small gadget, device; any unspecified object" (1909, cf. doohickey, still used in this sense).
hickory (n.): 1670s, American English, from Algonquian (perhaps Powhatan), shortening of pockerchicory or a similar name for this species of walnut. Old Hickory as the nickname of U.S. politician Andrew Jackson is first recorded 1827.
hickscorner (n.): "libertine scoffer at religion and the religious," c.1530, from the name of the character in a work of that name printed c.1512 by Wynkyn de Worde; from Hick, the common masc. nickname, + scorner (see scorn (v.)).
Hicksite: 1828, noun and adjective, in reference to a seceding group of American Quakers, from the name of their spiritual leader, Elias Hicks. The remainder were known as Orthodox Friends.
hid (v.): past tense and alternative past participle of hide (v.1).
How to entangle, trammel up and snare
Your soul in mine, and labyrinth you there
Like the hid scent in an unbudded rose?
Aye, a sweet kiss -- you see your mighty woes.

[Keats, "Lamia"]
hidage (n.): late 12c., from Anglo-Latin hidagium, from hida (see hide (n.2)); also see -age.
hidalgo (n.): "Spanish nobleman of secondary rank," 1590s, from Spanish hidalgo, from Old Spanish fidalgo, shortened from filho de algo "son (Latin filus) of someone (Latin aliquis)," perhaps an imitation of Arabic ibn-nas "son of people," a complimentary title. For alteration of f- and h- in Spanish, see hacienda.
hidden (adj.): past participle of hide (v.1); a Middle English formation (Old English had gehydd "hidden") on the model of ride/ridden, etc. Hidden persuaders (1957) was Vance Packard's term for "ad men."
hiddenness (n.): late 14c., from hidden + -ness.
hide (v.1): Old English hydan "to hide, conceal; preserve; hide oneself; bury a corpse," from West Germanic *hudjan (cf. Middle Dutch, Middle Low German huden), from PIE *keudh- (cf. Greek keuthein "to hide, conceal"), from root *(s)keu- "to cover, conceal" (see hide (n.1)). Hide and seek (by 1670s), children's game, replaced earlier all hid (1580s).
hide (n.1): "skin of a large animal," Old English hyd "hide, skin," from Proto-Germanic *hudiz (cf. Old Norse huð, Old Frisian hed, Middle Dutch huut, Dutch huid, Old High German hut, German Haut "skin"), related to Old English verb hydan "to hide," the common notion being of "covering."

All of this is from PIE root *(s)keu- "to cover, conceal" (cf. Sanskrit kostha "enclosing wall," skunati "covers;" Armenian ciw "roof;" Latin cutis "skin," scutum "shield," ob-scurus "dark;" Greek kytos "a hollow, vessel," keutho "to cover, to hide," skynia "eyebrows;" Russian kishka "gut," literally "sheath;" Lithuanian kiautas "husk," kutis "stall;" Old Norse sky "cloud;" Old English sceo "cloud;" Middle High German hode "scrotum;" Old High German scura, German Scheuer "barn;" Welsh cuddio "to hide").

The alliterative pairing of hide and hair (often negative, hide nor hair) was in Middle English (early 15c.), but earlier and more common was hide ne hewe, literally "skin and complexion ('hue')" (c.1200).
hide (n.2): "measure of land" (obsolete), Old English hid "hide of land," earlier higid, from hiw- "family" (cf. hiwan "household," hiwo "a husband, master of a household"), from Proto-Germanic *hiwido-, from PIE *keiwo- (cf. Latin civis "citizen"), from root *kei- "to lie; bed, couch; beloved, dear" (see cemetery, and cf. city).

The notion was of "amount of land needed to feed one free family and dependents," usually 100 or 120 acres, but the amount could be as little as 60, depending on the quality of the land. Often also defined as "as much land as could be tilled by one plow in a year." Translated in Latin as familia.
hideaway (n.): "small, secluded restaurant, etc.," 1929, from hide (v.1) + away. Earlier it meant "a fugitive person" (1871).
hidebound (adj.): 1550s, from hide (n.1) + past tense of bind (v.). Original reference is to emaciated cattle with skin sticking closely to backbones and ribs; metaphoric sense of "restricted by narrow attitudes" is first recorded c.1600.
hideosity (n.): "a very ugly thing," 1807, from hideous on model of monstrosity, etc.
hideous (adj.): c.1300, "terrifying, horrible, dreadful," from Anglo-French hidous, Old French hideus, earlier hisdos "hideous, horrible, awful, frightening" (11c.; Modern French hideux), from hisda "horror, fear," perhaps of Germanic origin; or else from Vulgar Latin *hispidosus, from Latin hispidus "shaggy, bristly," "[b]ut this presents numerous difficulties" [OED]. Meaning "repulsive" is late 14c.
hideously (adv.): mid-14c., from hideous + -ly (2).
hideousness (n.): late 14c., from hideous + -ness.
hideout (n.): also hide-out, "a hiding place," 1885, American English, from hide (v.) + out. The phrase hide out "conceal (oneself) from the authorities" is attested from 1870, American English (in reference to Northern draft dodgers in the Civil War).
hiding (n.1): "concealment," early 13c., verbal noun from hide (v.1). Hiding place is from mid-15c.; an Old English word for this was hydels.
hiding (n.2): "a flogging," 1809, from hide (n.1), perhaps in reference to a whip or thong made of animal hide. Old English had hyde ðolian "to undergo a flogging," and hydgild "fine paid to save one's skin (from a punishment by flogging)." The English expression a hiding to nothing (by 1905) referred to a situation where there was disgrace in defeat and no honor in victory.
hidy-hole (n.): 1817, altered from hiding-hole; from hiding (n.1) + hole (n.).
hie (v.): Old English higian "strive, hasten," originally "to be intent on," from Proto-Germanic *hig- (cf. Middle Dutch higen "to pant," Middle Low German hichen, German heichen). Related: Hied; hies; hieing.