Online Etymology Dictionary

heads-up (adj.): "clever, alert," 1926, from warning cry "heads up!" (i.e. "look up!"). As a noun, "a notification, a warning," by 1988.
headsman (n.): "executioner," c. 1600, from genitive of head (n.) + man (n.). Used earlier in sense "chief, leader" (c. 1400).
headstone (n.): c. 1400, "cornerstone," from head (adj.) + stone (n.). Meaning "upright stone at the head of a grave" is 1775, from head (n.).
headstrong (adj.): "determined to have one's way," late 14c., from head (n.) + strong. Compare Old English heafodbald "impudent," literally "head-bold." Strongheaded is attested from c. 1600.
headwaters (n.): attested 1530s, then not again until 1792 (in descriptions of Kentucky), so possibly the modern word is a re-formation; see head (n.) "origin of a river" + water (n.1).
headway (n.): c. 1300, "main road, highway," from Old English heafodweg; see head (adj.) + way (n.). Sense of "motion forward" first attested 1748, short for ahead-way; ultimately nautical (compare leeway).
heady (adj.): late 14c., "headstrong, hasty, impetuous," from head (n.) + adj. suffix -y (2). First recorded 1570s in sense of "apt to go to the head." Related: Headily; headiness.
heal (v.): Old English hælan "cure; save; make whole, sound and well," from Proto-Germanic *hailjan (source also of Old Saxon helian, Old Norse heila, Old Frisian hela, Dutch helen, German heilen, Gothic ga-hailjan "to heal, cure"), literally "to make whole," from PIE *kailo- "whole" (see health). Intransitive sense from late 14c. Related: Healed; healing.
heal-all (n.): 1570s, "universal remedy," from heal + all; applied since 1814 to various plants supposed to possess healing virtues. The native word for panacea.
healer (n.): late Old English, "one who heals," especially "savior, Jesus," agent noun from heal (v.). As "a curative medicine" from late 14c. The usual Old English noun for Jesus as savior was hæland (Middle English healend), a noun use of a present participle, being a rough translation of the name (see Joshua) or of Latin salvator.
healing (n.): "restoration to health," Old English hæling, verbal noun from heal (v.). Figurative sense of "restoration of wholeness" is from early 13c.; meaning "touch that cures" is from 1670s.
health (n.): Old English hælþ "wholeness, a being whole, sound or well," from Proto-Germanic *hailitho, from PIE *kailo- "whole, uninjured, of good omen" (source also of Old English hal "hale, whole;" Old Norse heill "healthy;" Old English halig, Old Norse helge "holy, sacred;" Old English hælan "to heal"). With Proto-Germanic abstract noun suffix *-itho (see -th (2)). Of physical health in Middle English, but also "prosperity, happiness, welfare; preservation, safety." An abstract noun to whole, not to heal. Meaning "a salutation" (in a toast, etc.) wishing one welfare or prosperity is from 1590s. Health food is from 1848.
health-care (n.): also healthcare, 1917, originally in reference to the German Empire, from health + care (n.).
healthful (adj.): late 14c., "wholesome, curative, saving, serving to promote health," from health + -ful. Meaning "free from disease, healthy" is attested from 1540s but is rare. Related: Healthfully; healthfulness.
healthy (adj.): 1550s, "being in a sound state;" also "conducive to health," from health + -y (2). Earlier in the same sense was healthsome (1530s). Related: Healthily; healthiness.
It is wrong to say that certain articles of food are healthy or unhealthy. Wholesome and unwholesome are the right words. A pig may be healthy or unhealthy while alive; but after he is killed and becomes pork, he can enjoy no health, and suffer no sickness. [Eliza Leslie, "Miss Leslie's Behaviour Book," Philadelphia, 1839]
Healthsome is from 1530s in the sense "bestowing health."
heap (n.): Old English heap "pile (of things); great number, crowd, multitude (of persons)," from West Germanic *haupaz (source also of Old Saxon hop, Old Frisian hap, Middle Low German hupe, Dutch hoop, German Haufe "heap"), of uncertain origin. The group is perhaps related to Old English heah "high" (see high), but OED suggests a common origin with Latin cubare "lie down." Slang meaning "old car" is attested from 1924. Earlier it meant "slovenly woman" (1806). As a characteristic word in American Indian English speech, "a lot, a great deal," by 1832.
One grain of sand does not make a heap. A second grain of sand added to the first does not make a heap. Indeed each and every grain of sand, when added to the others, does not make a heap which was not a heap before. Therefore, all the grains of sand in existence can still not a heap make. [the fallacy of the heap]
heap (v.): Old English heapian "collect, heap up, bring together;" from heap (n.). Related: Heaped; heaping. Compare Old High German houfon, German haufen "to heap," also a verb from a noun.
hear (v.): Old English heran (Anglian), (ge)hieran, hyran (West Saxon) "to hear, perceive by the ear, listen (to), obey, follow; accede to, grant; judge," from Proto-Germanic *hauzjan (source also of Old Norse heyra, Old Frisian hora, Dutch horen, German hören, Gothic hausjan), from PIE *kous- "to hear" (see acoustic). The shift from *-z- to -r- is a regular feature in some Germanic languages.

For the vowels, see head (n.); spelling distinction between hear and here developed 1200-1550. Meaning "be told, learn by report" is from early 14c. Old English also had the excellent adjective hiersum "ready to hear, obedient," literally "hear-some" with suffix from handsome, etc. Hear, hear! (1680s) originally was imperative, an exclamation to call attention to a speaker's words ("hear him!"); now a general cheer of approval. To not hear of "have nothing to do with" is from 1754.
heard: past tense and past participle of hear, Old English herde. To have heard of "know about" is from 1907.
hearer (n.): mid-14c., agent noun from hear.
hearing (n.): early 13c., "perception of sound by ear, action of listening," verbal noun from hear (v.). Meaning "a listening to evidence in a court of law" is from 1570s. Hearing-aid is from 1908.
hearken (v.): late Old English heorcnian "to give ear, listen" (intransitive); hear with attention" (transitive), a suffixed form of *heorcian (root of hark); from Proto-Germanic *hausjan (see hear). Harken is the usual spelling in U.S. and probably is better justified by etymology; OED says preference for hearken in British use likely is from influence of hear.
hearkening (n.): Old English heorcnung "a harkening, listening; power of hearing" (see hearken).
hearsay (n.): "information communicated by another, gossip," mid-15c., from phrase to hear say (Middle English heren seien, Old English herdon secgan). The notion is "hear (some people) say;" from hear (v.) + say (v.). As an adjective from 1570s. Hearsay evidence (1670s) is that which the witness gives not from his own perception but what was told to him. Compare similar formation in Dutch hooren zeggen, German hörensagen.
hearse (n.): c. 1300 (late 13c. in Anglo-Latin), "flat framework for candles, hung over a coffin," from Old French herse, formerly herce "large rake for breaking up soil, harrow; portcullis," also "large chandelier in a church," from Medieval Latin hercia, from Latin hirpicem (nominative hirpex) "harrow," a rustic word, from Oscan hirpus "wolf," supposedly in allusion to its teeth. Or the Oscan word may be related to Latin hirsutus "shaggy, bristly."

The funeral display is so called because it resembled a harrow (hearse in its sense of "portcullis" is not attested in English before 15c.). Sense extended to other temporary frameworks built over dead people, then to "vehicle for carrying a dead person to the grave," a sense first recorded 1640s. For spelling, see head (n.).
heart (n.): Old English heorte "heart (hollow muscular organ that circulates blood); breast, soul, spirit, will, desire; courage; mind, intellect," from Proto-Germanic *herton- (source also of Old Saxon herta, Old Frisian herte, Old Norse hjarta, Dutch hart, Old High German herza, German Herz, Gothic hairto), from PIE *kerd- (1) "heart" (source also of Greek kardia, Latin cor, Old Irish cride, Welsh craidd, Hittite kir, Lithuanian širdis, Russian serdce "heart," Breton kreiz "middle," Old Church Slavonic sreda "middle").

Spelling with -ea- is c. 1500, reflecting what then was a long vowel, and the spelling remained when the pronunciation shifted. Most of the modern figurative senses were present in Old English, including "memory" (from the notion of the heart as the seat of all mental faculties, now only in by heart, which is from late 14c.), "seat of inmost feelings; will; seat of emotions, especially love and affection; seat of courage." Meaning "inner part of anything" is from early 14c. In reference to the conventional heart-shape in illustration, late 15c.; heart-shaped is from 1744.

Heart attack attested from 1875; heart disease is from 1864. The card game hearts is so called from 1886. To have one's heart in the right place "mean well" is from 1774. Heart and soul "one's whole being" is from 1650s. To eat (one's own) heart "waste away with grief, resentment, etc." is from 1580s.
heart (v.): Old English hiertan "give heart to," from heart (n.). Shakespeare used it as "take to heart" (c. 1600); 1866 of cabbages, "to form a heart." Meaning "to love" is by 1993, from the popular New York state tourism campaign that used the heart symbol in place of the word "love."
heart-ache (n.): also heartache, late Old English heort ece "physical pain in or near the heart;" from heart (n.) + ache (n.). Sense of "anguish of mind" is from c. 1600; Old English did, however, have heartsarnes "grief," literally "heart-soreness;" Middle English had herte-smerte "sorrow, contrition."
heart-beat (n.): also heartbeat, 1850, "a pulsation of the heart," from heart (n.) + beat (n.). From its coinage used as a figure for "a very brief time."
heart-breaker (n.): also heartbreaker, 1660s, originally "a fetching lock of hair;" of persons, "one who breaks hearts," from 1863; agent noun formation; see heartbreak.
heart-felt (adj.): also heartfelt, "profoundly felt, deep, sincere," 1734, from heart (n.) + past tense of feel (v.).
heart-rending (adj.): also heartrending, 1680s, from heart (n.) + present participle of rend (v.). Related: Heart-rendingly.
heart-strings (n.): also heartstrings, late 15c., in old anatomy, "the tendons and nerves that brace the heart;" from heart (n.) + string (n.). Transferred and figurative sense "strongest affections, most intense feelings" is from 1590s.
heart-throb (n.): also heartthrob, 1821, "passion, affection;" 1839 in literal sense, "a beat of the heart," from heart (n.) + throb (n.). Of persons who inspire romantic feelings, from 1928; used 1910s of a quality that appeals to sentiment or emotion in newspapers, advertising, etc..
heart-to-heart (adj.): 1867; see heart (n.) in figurative sense of "inmost feelings."
heart-warming (adj.): also heartwarming, 1620s, from heart (n.) + present participle of warm (v.).
heart-wood (n.): also heartwood, 1801, from heart (n.) in the sense "central part of a tree" (c. 1400) + wood (n.).
heartbreak (n.): also heart-break, "overwhelming grief or sorrow," 1570s, from heart (n.) + break (n.). Expression break (someone's) heart is from c. 1400. Related: Heartbreaking.
heartbroken (adj.): also heart-broken, "deeply grieved," 1580s, past participle formation from heartbreak. Related: Heartbrokenly; heartbrokenness.
heartburn (n.): mid-13c., herte-brine "lust," later "burning sensation in the esophagus, indigestion" (mid-15c.); see heart (n.) + burn (n.). Compare cardiac for confusion of "heart" and "stomach." A Middle English alternative was herte-brenning "anger, bitterness" (c. 1400), also "heartburn" (mid-15c.).
hearten (v.): 1520s, "put heart into" (transitive), from heart (n.) in the figurative sense + -en (1). Intransitive sense "to cheer up" is from 1708. Related: Heartened; heartening. Earlier verb was simply heart (Old English).
heartful (adj.): "devout, earnest," mid-14c., from heart (n.) + -ful. Related: Heartfully.
hearth (n.): Old English heorð "hearth, fireplace, part of a floor on which a fire is made," also in transferred use "house, home, fireside," from West Germanic *hertho "burning place" (source also of Old Saxon and Old Frisian herth, Middle Dutch hert, Dutch haard, German Herd "floor, ground, fireplace"), from PIE *kerta-, from root *ker- (4) "heat, fire" (see carbon). Hearth-rug is from 1824. Hearth-stone is from early 14c.
heartily (adv.): c. 1300, from hearty + -ly (2).
heartland (n.): also heart-land, 1904, first recorded in geo-political writings of English geographer H.J. MacKinder (1861-1947), from heart (n.) in figurative sense "center, core" + land (n.).
heartless (adj.): Old English heortleas "dispirited, dejected;" see heart (n.) + -less. In Middle English with expanded senses "lacking in courage; foolish; listless; half-hearted; sluggish." Sense of "callous, cruel, wanting in kindly feeling" is not certainly attested before Shelley used it thus in 1816. Literal meaning "lacking a heart, lifeless" (mid-15c.) is rare. Related: Heartlessly; heartlessness. Similar formation in Dutch harteloos, German herzlos.
heartsick (adj.): also heart-sick, "despondent," late 14c., from heart (n.) + sick (adj.). Old English heortseoc meant "ill from heart disease."
hearty (adj.): late 14c., "courageous; spirited, zealous, from the heart;" also "loyal, faithful; sagacious, wise," from heart (n.) in its broad figurative senses + -y (2). Meaning "affording abundant nourishment" is from 1610s. Related: Heartiness.
heat (n.): Old English hætu, hæto "heat, warmth, quality of being hot; fervor, ardor," from Proto-Germanic *haita- "heat" (source also of Old Saxon hittia, Old Norse hiti, Old Frisian hete, German hitze "heat," Gothic heito "fever"), from PIE *kaid-, from root *kai- "heat." The same root is the source of Old English hat "hot" and hæða "hot weather."

Meaning "a single course in a race," especially a horse race, is from 1660s, perhaps from earlier figurative sense of "violent action; a single intense effort" (late 14c.), or the meaning "run given to a horse to prepare for a race" (1570s). The latter word over time was extended to "division of a race or contest when there are too many contestants to run at once," the winners of each heat then competing in a final race.

Meaning "sexual excitement in animals" is from 1768, especially of females, corresponding to rut in males. Meaning "trouble with the police" attested by 1920. Heat wave "period of excessive hot weather" first attested 1890; earlier in reference to solar cycles. Heat-stroke is from 1858. Heat-seeking (adj.) of missiles, etc., is by 1955. Red heat, white heat are in reference to the color of heated metals, especially iron.
heat (v.): Old English hætan "to make hot; to become hot," from Proto-Germanic *haita- (see heat (n.)). Related: Heated (with many variants in Middle English); heating. Compare Middle Dutch heeten, Dutch heten, German heizen "to heat."