Online Etymology Dictionary

Hertfordshire: Old English Heortfordscir, from Herutford (731), literally "ford frequented by harts;" see hart (n.) + ford (n.).
Hertz: unit of frequency equal to one cycle per second, 1928, named in reference to German physicist Heinrich Hertz (1857-1894). Related: Hertzian.
Herzegovina: former Austrian duchy in the Balkans, from Old Serbian herceg "duke" (related to Modern German Herzog) + possessive ending -ov + -ina "country." Related: Herzegovinian.
hesitance (n.): c. 1600, from Latin haesitantia (see hesitancy).
hesitancy (n.): 1610s, from Latin haesitantia "action of stammering," from haesitantem (nominative haesitans) "stammering," present participle of haesitare "to stick fast, stammer" (see hesitation).
hesitant (adj.): 1640s, probably a back-formation from hesitancy, or else from Latin haesitantem. Related: Hesitantly.
hesitate (v.): 1620s, from Latin haesitatus, past participle of haesitare "to stick fast; to hesitate; to stammer" (see hesitation). Related: Hesitated; hesitating; hesitatingly.
hesitation (n.): c. 1400, from Old French hesitacion or directly from Latin haesitationem (nominative haesitatio) "a hesitation, stammering," figuratively "irresolution, uncertainty," noun of action from past participle stem of haesitare "stick fast, remain fixed; stammer in speech," figuratively "hesitate, be irresolute, be at a loss, be undecided," frequentative of haerere "stick, cling," from PIE root *ghais- "to adhere, hesitate" (source also of Lithuanian gaistu "to delay, tarry").
hesitative (adj.): "given to hesitation, showing hesitation," 1795, from hesitate + -ive. Related: Hesitatively.
Hesperides: 1590s, from Greek, "daughters of the Hesperus," name given to the nymphs (variously numbered but originally three) who tended the garden with the golden apples. Their name has been mistakenly transferred to the garden itself.
The Gardens of the Hesperides with the golden apples were believed to exist in some island in the ocean, or, as it was sometimes thought, in the islands on the north or west coast of Africa. They were far-famed in antiquity; for it was there that springs of nectar flowed by the couch of Zeus, and there that the earth displayed the rarest blessings of the gods; it was another Eden. As knowledge increased with regard to western lands, it became necessary to move this paradise farther and farther out into the Western Ocean. [Alexander Murray, "Manual of Mythology," 1888]
Related: Hesperidean; Hesperidian.
Hesperus: late 14c., poetic for "the evening star," from Latin Hesperus, from Greek hesperos (aster) "the evening (star)," from PIE *wes-pero- "evening, night" (see vesper). Related: Hesperian. Hence Latin and Greek Hesperia "the land of the west," "applied by the Greeks to Italy, by the Romans to Spain or regions beyond" [Century Dictionary].
Hessian (n.): "resident of the former Landgraviate of Hessen-Kassel," western Germany; its soldiers being hired out by the ruler to fight for other countries, especially the British during the American Revolution, the name Hessians by 1835 in U.S. became synonymous (unjustly) with "mercenaries." Hessian fly (Cecidomyia destructor) was a destructive parasite the ravaged U.S. crops late 18c., so named 1787 in erroneous belief that it was carried into America by the Hessians.

The place name is from Latin Hassi/Hatti/Chatti, the Latinized form of the name of the Germanic people the Romans met in northern Germany (Greek Khattoi). The meaning of the name is unknown. Part of Arminius's coalition at the Battle of Teutoburger Wald (9 C.E.), they later merged with the Franks. They are mentioned in Beowulf as the Hetwaras. The state was annexed to Prussia in 1866 and is not to be confused with the Grand Duchy of Hesse-Darmstadt.
hessonite (n.): "cinnamon-stone," a variety of garnet, 1820, from French essonit (1817), from Greek heson "less" + -ite (2). So called because it is lighter than other similar minerals.
hest (n.): "bidding, command," Old English hæs "bidding, behest, command," from Proto-Germanic *hait-ti-, from *haitan "to call, name" (see hight (v.)). With excrescent -t added in Middle English on model of other pairings (compare wist/wesan, also whilst, aghast).
Hestia: goddess of the hearth, from Greek hestia "hearth, house, home, family" (see vestal).
het (adj.): "heated," archaic, late 14c., from variant past participle of heat (v.). Compare lead (v.)/led, etc.
hetaera (n.): 1820, "mistress," from Medieval Latin hetaera, from Greek hetaira "female companion," fem. of hetairos "comrade, companion, good friend," from PIE *swet-aro-, suffixed form of root *s(w)e-, pronoun of the third person and reflexive (see idiom). Classical plural would be hetaerae or herairai.

Typically a slave or foreign woman devoted to private or public entertainment. In Athens, where citizens could legally marry only daughters of full citizens, opposed to "lawful wife," and thus embracing everything from "concubine" to "courtesan."
hetaerocracy (n.): "rule of courtesans," 1859, from hetaera + -cracy.
hetero (adj.): 1933, short for heterosexual.
hetero-: before vowels heter-, word-forming element meaning "other, different," from Greek heteros "the other (of two), another, different; second; other than usual." It is a compound; the first element means "one, at one, together," from PIE *sem- (1) "one" (see same); the second is cognate with the second element in Latin al-ter, Gothic an-þar, Old English o-ðer "other."

Compounds in classical Greek show the range of the word there: Heterokretes "true Cretan," (that is, of the old stock); heteroglossos "of foreign language;" heterozelos "zealous for one side;" heterotropos "of a different sort or fashion," literally "turning the other way;" heterophron "raving," literally "of other mind."
heteroclite (adj.): in reference to a word (especially a noun) irregularly inflected, 1570s, from French hétéroclite, from Late Latin heteroclitus, from Greek heteroklitos "irregularly inflected," from hetero- "different" (see hetero-) + verbal adjective from klinein "to lean" (see lean (v.)). Figuratively, of persons, "deviating from the ordinary," from 1590s.
heterodox (adj.): "not in accordance with established doctrines," 1630s, from Greek heterodoxos "of another or different opinion," from heteros "the other" (see hetero-) + doxa "opinion," from dokein "to appear, seem, think" (see decent).
heterodoxy (n.): 1650s, from Greek heterodoxia "error of opinion," from heterodoxos (see heterodox).
heterogeneity (n.): 1640s, from heterogeneous + -ity, or else from Medieval Latin heterogeneitas, from heterogeneus.
heterogeneous (adj.): "diverse in kind or nature," 1620s, from Medieval Latin heterogeneus, from Greek heterogenes, from heteros "different" (see hetero-) + genos "kind, gender, race stock" (see genus). Earlier in same sense was heterogeneal (c. 1600). Related: Heterogeneously; heterogeneousness.
heterogenous (adj.): 1690s, less-accepted form of heterogeneous. Related: Heterogeneity.
heterography (n.): "incorrect spelling," 1783; see hetero- "other, different" + -graphy. Also "inconsistent but current spellings within a language, the use of the same letter with different value in different words or positions" (as English, in all ages), 1847.
heteromorphic (adj.): "having different or dissimilar forms, undergoing complete metamorphosis" (as insects do), 1851; see hetero- "other, different" + morphic.
heteronomy (n.): 1798, "subjection to the rule of another power," from hetero- "other, different" + -nomy, from Greek nomos "law" (see numismatics). Related: Heteronomic; heteronomous (1817).
heteronym (n.): "word having the same spelling as another but with a different sound and meaning," 1889, also "a thing's name in one language that is an exact translation of its name in another" (1885); from hetero- "other, different" + -onym "name" (see name (n.)). Distinction from a homonym is that a homonym has not the same spelling. Related: Heteronymic; heteronymous.
heterophemy (n.): "the (unintentional) use of some other word or phrase in place of the one that was meant," 1875 (Grant White), from hetero- "other, different" + Greek pheme "utterance," from PIE root *bha- (2) "to speak, tell, say" (see fame (n.)).
heterosexism (n.): "discrimination or prejudice against homosexuals," by 1975 in feminist and lesbian writing; see heterosexual + sexism. Related: Heterosexist (1977).
heterosexual (adj.): 1892, in C.G. Craddock's translation of Krafft-Ebbing's "Psychopathia Sexualis," a hybrid; see hetero- "other, different" + sexual. The noun is recorded from 1920, but not in common use until 1960s. Colloquial shortening hetero is attested from 1933.
heterosexuality (n.): 1894; see heterosexual + -ity.
heterotroph (n.): 1900, from German (1892), from hetero- "other" + Greek trophos "feeder" (see -trophy). Related: Heterotrophic (1884); heterotrophism (1885); heterotrophy.
heterotrophy (n.): 1888, from German (1885); see hetero- "other" + -trophy "nourishment." Used especially of plants that depend for food on a fungus.
heterozygous (adj.): 1889, from hetero- "other, different" + zygote + -ous. Related: Heterozygote (1902).
hetman (n.): "Cossack commander," 1710, from Polish hetman, apparently from an early form of German Hauptmann "captain," literally "headman," from Haupt "head" (see head (n.)) + Mann (see man (n.)).
heuristic (adj.): "serving to discover or find out," 1821, irregular formation from Greek heuriskein "to find; find out, discover; devise, invent; get, gain, procure" (from PIE *were- (2) "to find;" cognate with Old Irish fuar "I have found") + -istic. As a noun, from 1860. Greek had heuretikos "inventive," also heurema "an invention, a discovery; that which is found unexpectedly."
heuristics (n.): "study of heuristic methods," 1897, from heuristic (n.); also see -ics.
hew (v.): Old English heawan "to chop, hack, gash, strike with a cutting weapon or tool" (class VII strong verb; past tense heow, past participle heawen), earlier geheawan, from Proto-Germanic *hawwan (source also of Old Norse hoggva, Old Frisian hawa, Old Saxon hauwan, Middle Dutch hauwen, Dutch houwen, Old High German houwan, German hauen "to cut, strike, hew"), from PIE *kau- "to hew, strike," a root more widely developed in Slavic (source also of Old Church Slavonic kovo, Lithuanian kauti "to strike, beat, fight;" Polish kúc "to forge," Russian kovat' "to strike, hammer, forge;" Latin cudere "to strike, beat;" Middle Irish cuad "beat, fight").

Weak past participle hewede appeared 14c., but hasn't yet entirely displaced hewn. Seemingly contradictory sense of "hold fast, stick to" (in phrase hew to), 1891, developed from earlier figurative phrase hew to the line "stick to a course," literally "cut evenly with an axe or saw." Related: Hewed; hewing.
hewer (n.): "cutter" (of stone or wood), late 14c. (mid-12c. as a surname), agent noun from hew (v.). Hewers of wood and drawers of water to describe the lowliest sort of physical laborers is from Joshua ix:12. Old English has it as wuduheawerum and þam þe wæter beraþ; the modern form of the phrase is from 1535.
hewn (adj.): 14c., from strong past participle of hew.
hex (v.): 1830, American English, from Pennsylvania German hexe "to practice witchcraft," from German hexen "to hex," related to Hexe "witch," from Middle High German hecse, hexse, from Old High German hagazussa (see hag). Noun meaning "magic spell" is first recorded 1909; earlier it meant "a witch" (1856).
hexa-: before vowels and in certain chemical compound words hex-, word-forming element meaning "six," from Greek hexa-, comb. form of hex "six," from PIE root *sweks- (see six).
hexadecimal (adj.): 1952, in reference to a numeral system based on 16, not 10; from hexa- + decimal. From 1970 as a noun.
hexagon (n.): 1560s, from Latin hexagonum, from Greek hexagonon, neuter of hexagonos "six-cornered, hexagonal," from hex "six" (see hexa-) + gonia "angle" (see -gon).
hexagonal (adj.): 1570s, from hexagon + -al (1). Related: Hexagonally.
hexagram (n.): 1826 as a type of geometric figure, from hexa- + -gram. I Ching sense attested from 1804.
hexameter (adj.): 1540s, from Latin hexameter, from Greek hexametros "of six measures, composed of six feet; hexameter," from hex "six" (see six) + metron "meter" (see meter (n.2)). As a noun, "a verse consisting of six measures," from 1570s. Chaucer has the word as exametron. Related: Hexametric.