Online Etymology Dictionary

hedonism (n.): 1828 in reference to the philosophy; 1844 as "self-indulgence," from Greek hedone "pleasure" (see hedonist) + -ism.
The doctrine of Aristippus and the Cyrenaic school of Greek philosophers, that the pleasure of the moment is the only possible end, that one kind of pleasure is not to be preferred to another, and that a man should in the interest of pleasure govern his pleasures and not be governed by them; hence, that ethical doctrine which regards pleasure or happiness as the highest good. ... Egoistic hedonism considers only the pleasure of the individual; altruistic hedonism takes into account that of others. [Century Dictionary]
hedonist (n.): 1806, in reference to the Cyrenaic school of philosophy that deals with the ethics of pleasure; with -ist + Greek hedone "pleasure, delight, enjoyment; a pleasure, a delight," which is related to hedys "sweet" and cognate with Latin suavis, from PIE *swad-ona, suffixed form of root *swad- "sweet, pleasant" (see sweet (adj.)). Meaning "one who regards pleasure as the chief goal of life" is from 1854. A hedonist is properly the follower of any ethical system in which some sort of pleasure ranks as the highest good. The Epicurean identifies this pleasure with the practice of virtue.
hedonistic (adj.): 1849, from hedonist + -ic. The earlier adjectival form was hedonic. By 1901 in psychology, "of the nature of pleasure-seeking."
Hedwig: fem. proper name, German, from Old High German Haduwig, a compound of two words both of which mean "strife, struggle." Second element also that of Ludwig.
hee-haw: also heehaw, first recorded 1815 (as Hiu Haw), probably imitative of sound of donkey's bray (compare French hinham). As "a loud laugh" from 1843.
heebie-jeebies (n.): 1923, said to have been coined by U.S. cartoonist Billy De Beck (1890-1942), creator of "Barney Google."
heed (v.): Old English hedan "observe; to take care, attend, care for, protect, take charge of," from West Germanic *hodjan (source also of Old Saxon hodian, Old Frisian hoda, Middle Dutch and Dutch hoeden, Old High German huotan, German hüten "to guard, watch"), from PIE *kadh- "to shelter, cover" (see hat). Related: Heeded; heeding.
heed (n.): "careful attention, notice, regard," early 14c., from heed (v.). Survives only in literary use, in compounds, and as the object of verbs (take heed, etc.).
heedful (adj.): "cautious, wary," 1540s, from heed (n.) + -ful.
heedless (adj.): "without regard," 1570s, from heed (n.) + -less. Related: Heedlessly; heedlessness. Spenser has heedlesshood.
heel (n.1): "back of the foot," Old English hela, from Proto-Germanic *hanhilon (source also of Old Norse hæll, Old Frisian hel, Dutch hiel), from PIE *kenk- (3) "heel, bend of the knee" (source also of Old English hoh "hock").

Meaning "back of a shoe or boot" is c. 1400. Down at heels (1732) refers to heels of boots or shoes worn down and the owner too poor to replace them. For Achilles' heel "only vulnerable spot" see Achilles. To "fight with (one's) heels" (fighten with heles) in Middle English meant "to run away."
heel (v.2): "to lean to one side," usually in reference to a ship, re-spelled 16c. from Middle English hield (probably by misinterpretation of -d as a past tense suffix), from Old English hieldan "incline, lean, slope," from Proto-Germanic *helthijan (source also of Middle Dutch helden "to lean," Dutch hellen, Old Norse hallr "inclined," Old High German halda, German halde "slope, declivity"). Related: Heeled; heeling.
heel (n.2): "contemptible person," 1914 in U.S. underworld slang, originally "incompetent or worthless criminal," perhaps from a sense of "person in the lowest position" and thus from heel (n.1).
heel (v.1): of a dog, "to follow or stop at a person's heels," 1810, from heel (n.1). Also see heeled.
heel (v.3): "furnish with a heel," of a shoe, boot, etc., c.1600, from heel (n.1). Related: Heeled; heeling.
heel-tap (n.): also heeltap, 1680s, "one of the bits of leather that are stacked up to make a shoe heel" (see heel (n.1)); meaning "bit of liquor left in a glass or bottle" first recorded 1767; the exact connection is uncertain unless it be "the last or final part." Related: Heeltaps.
A jolly dog, is one who has no conversation in company, but "fill about, what's the toast, damn your heel-taps," and roars out an obscene ballad when he gets drunk. ["The Batchelor," March 28, 1767]
heeled (adj.): "provided with money," 1880, American English Western slang, from earlier sense "furnished with a gun, armed" (1866). This is perhaps transferred from the sense "furnish (a gamecock) with a heel-like spur" (1560s), which was still in use in 19c., a special use of heel (v.3).
heeler (n.): 1660s, "one who puts heels on shoes and boots," agent noun from heel (n.1). Meaning "unscrupulous political lackey" is U.S. slang from 1877. The notion is of one who follows at the heels of a political boss, and it likely was coined with the image of a dog in mind. See heel (v.1).
heffalump (n.): imaginary creature, 1926 (A.A. Milne), from a child's pronunciation of elephant.
heft (n.): mid-15c., "weight, heaviness, quality of weight," from heave (v.) on analogy of thieve/theft, weave/weft, etc. Also influenced by heft, obsolete past participle of heave.
heft (v.): "to lift, try the weight of," 1660s, from heft (n.). Related: Hefted; hefting.
hefty (adj.): "having considerable weight," 1866, from heft (n.) + -y (2). Related: Heftiness.
Hegelian (adj.): 1832, "pertaining to German philosopher Georg Wilhelm Friedrich Hegel" (1770-1831). As a noun from 1836.
hegemon (n.): 1897, originally with reference to the position of Great Britain in the world, from Greek hegemon "an authority, leader, sovereign" (see hegemony).
hegemonic (adj.): "ruling, predominant, supreme," 1650s, from Latinized form of Greek hegemonikos "ready to lead, capable of command," from hegemon "leader, an authority" (see hegemony). Earlier in same sense was hegemonical (1610s).
hegemonism (n.): 1965, in reference to a policy of political domination, on model of imperialism; see hegemony + -ism.
hegemonist (n.): "one who advocates a political policy of hegemony," 1898 (in reference to Prussia in Germany); see hegemony + -ist.
hegemony (n.): 1560s, "preponderance, dominance, leadership," originally of predominance of one city state or another in Greek history; from Greek hegemonia "leadership, a leading the way, a going first;" also "the authority or sovereignty of one city-state over a number of others," as Athens in Attica, Thebes in Boeotia; from hegemon "leader, an authority, commander, sovereign," from hegeisthai "to lead," perhaps originally "to track down," from PIE *sag-eyo-, from root *sag- "to seek out, track down, trace" (see seek). In reference to modern situations from 1850, at first of Prussia in relation to other German states.
hegira (n.): flight of Muhammad from Mecca to Medina (July 16, 622 C.E.), the event from which the Islamic calendar reckons, 1580s, from Medieval Latin hegira, from Arabic hijrah "departure," from hajara "to depart."
heh (interj.): mid-15c., originally an exclamation of emotions such as sorrow or surprise. As the sound of a light laugh by 1808.
heifer (n.): Old English heahfore (West Saxon); Northumbrian hehfaro, heffera (plural), "heifer," of unknown origin, not found outside English.

The first element seems to be heah "high," which is common in Old English compounds with a sense of "great in size." The second element might be from a fem. form of Old English fearr "bull," from Proto-Germanic *farzi-, from PIE root *pere- (1) "to produce, bring forth." Or it might be related to Old English faran "to go" (giving the whole a sense of "high-stepper"); but there are serious sense difficulties with both conjectures. Liberman offers this alternative:
Old English seems to have had the word *hægfore 'heifer.' The first element (*hæg-) presumably meant 'enclosure' (as do haw and hedge), whereas -fore was a suffix meaning 'dweller, occupant' ....
In modern use, a female that has not yet calved, as opposed to a cow (n.), which has, and a calf (n.1), which is an animal of either sex not more than a year old. As derisive slang for "a woman, girl" it dates from 1835.
heigh-ho (interj.): c. 1400 as part of the refrain of a song; by 1550s as an exclamation to express yawning, sighing, etc.; see hey.
height (n.): Old English hiehþu, Anglian hehþo "highest part or point, summit; the heavens, heaven," from root of heah "high" (see high) + -itha, Germanic abstract noun suffix (as in width, depth; see -th (2)). Compare Old Norse hæð, Middle Dutch hoochte, Old High German hohida, Gothic hauhiþa "height." Meaning "distance from bottom to top" is from late 13c. Meaning "excellence, high degree of a quality" is late 14c. Century Dictionary says "there is no reason for the distinction of vowel between high and height. The modern pronunciation with -t emerged 13c. but wasn't established until 19c.; Milton used highth and heighth is still colloquial in English. Compare Dutch hoogte, Danish hjöde.
heighten (v.): mid-15c., heightenen, transitive, "to exalt, to honor or raise to high position," from height + -en (1). Intransitive sense of "to become higher" is from 1560s. Related: Heightened; heightening.
heighth (n.): obsolete or colloquial variant of height (q.v.).
heil (v.): "hail," German from Sieg Heil (q.v.). Middle English cognate heil was used as a salutation implying respect or reverence (c. 1200; see hail (interj.)).
Heimlich maneuver (n.): 1975, named for U.S. physician Henry Jay Heimlich (b. 1920).
Heimweh (n.): see homesickness.
Heinie (n.): also Heine, Hiney, 1904 as a typical name of a German man, North American slang, from pet form of common German masc. proper name Heinrich (see Henry). Brought to Europe in World War I by Canadian soldiers (British soldiers called the adversary Fritz).
heinie (n.): also heiney, slang for "the buttocks," by 1930s, of uncertain origin; perhaps a contraction of hind end.
heinous (adj.): late 14c., "hateful, odious, atrocious," from Old French hainos "inconvenient, awkward; hateful, unpleasant; odious" (12c., Modern French haineux), from haine "hatred, hate," from hair "to hate," from Frankish, from Proto-Germanic *hatjan, from PIE *kad- "sorrow, hatred" (see hate (v.)). Related: Heinously; heinousness.
heir (n.): "one who inherits, or has right of inheritance in, the property of another," c. 1300, from Anglo-French heir, Old French oir "heir, successor; heritage, inheritance," from Latin heredem (nominative heres) "heir, heiress" (see heredity). Heir apparent (late 14c.) has the French order of noun-adjective, though it was not originally so written in English. It is the heir of one still alive whose right is clear. After death the heir apparent becomes the heir-at-law. Related: Heir-apparency.
heiress (n.): 1650s, from heir + -ess. A female heir, but especially a woman who has inherited, or stands to inherit, considerable wealth.
heirless (adj.): c. 1400, from heir + -less.
heirloom (n.): early 15c., ayre lome, a hybrid from heir + loom (n.) in its original but now otherwise obsolete sense of "implement, tool," extended to mean "article." Technically, some piece of property that by will or custom passes down with the real estate. General sense of "anything handed down from generation to generation" is from 1610s.
Heisenberg: 1932 in reference to German physicist Werner Heisenberg (1901-1976), pioneer of quantum mechanics. His "uncertainty principle" (deduced in 1927) is that an electron may have a determinate position, or a determinate velocity, but not both.
heist (v.): 1943 (implied in heisted; heister "shoplifter, thief" is from 1927), American English slang, probably a dialectal alteration of hoist (v.) "to lift" in its slang sense of "shoplift," and/or its older British slang sense "to lift another on one's shoulders to help him break in." As a noun from 1930.
held: Old English heold, past tense and past participle of hold (v.).
Helen: fem. proper name, from French Hélène, from Latin Helena, from Greek Helene, fem. proper name, probably fem. of helenos "the bright one." In Greek legend, the sister of Castor and Pollux and wife of Menelaus, king of Sparta. Her elopement with Paris was the cause of the Trojan War. Among the top 10 popular names for girl babies in the U.S. born between 1890 and 1934.
Helena: fem. proper name, Latin form of Helen.