headquarters (n.) Look up headquarters at Dictionary.com
"residence of a military commander," 1640s, from head (adj.) + quarters. Headquarter as a verb is recorded from 1903. Related: Headquartered.
headroom (n.) Look up headroom at Dictionary.com
"space above the head," 1851, from head (n.) + room (n.).
heads-up (adj.) Look up heads-up at Dictionary.com
"clever, alert," 1952, from warning cry "heads up!" (i.e. "look up!"), attested by 1939.
headsman (n.) Look up headsman at Dictionary.com
"executioner," c. 1600, from genitive of head (n.) + man (n.). Used earlier in sense "chief, leader" (c. 1400).
headstone (n.) Look up headstone at Dictionary.com
c. 1400, "cornerstone," from head (adj.) + stone (n.). Meaning "upright stone at the head of a grave" is 1775, from head (n.).
headstrong (adj.) Look up headstrong at Dictionary.com
"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.) Look up headwaters at Dictionary.com
1530s; see head (n.) + water (n.1).
headway (n.) Look up headway at Dictionary.com
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.) Look up heady at Dictionary.com
late 14c., "headstrong, hasty, impetuous," from head (n.) + adj. suffix -y (2). First recorded 1570s in sense of "apt to go to the head."
heal (v.) Look up heal at Dictionary.com
Old English hælan "cure; save; make whole, sound and well," from Proto-Germanic *hailjan (cognates: Old Saxon helian, Old Norse heila, Old Frisian hela, Dutch helen, German heilen, Gothic ga-hailjan "to heal, cure"), literally "to make whole" (see health). Related: Healed; healing.
heal-all (n.) Look up heal-all at Dictionary.com
native word for panacea, 1570s, from heal + all; applied to various plants since 1853.
healer (n.) Look up healer at Dictionary.com
late Old English, "one who heals," especially "savior, Jesus," agent noun from heal (v.). As "a curative medicine" from late 14c.
healing (n.) Look up healing at Dictionary.com
"restoration to health," Old English hæling; see heal. Figurative sense of "restoration of wholeness" is from early 13c.; meaning "touch that cures" is from 1670s.
health (n.) Look up health at Dictionary.com
Old English hælþ "wholeness, a being whole, sound or well," from Proto-Germanic *hailitho, from PIE *kailo- "whole, uninjured, of good omen" (cognates: 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 1882.
healthcare (n.) Look up healthcare at Dictionary.com
also health care, 1940, U.S. government-ese, from health + care (n.).
healthful (adj.) Look up healthful at Dictionary.com
late 14c., "wholesome, curative, saving," from health + -ful. Related: Healthfully; healthfulness.
healthily (adv.) Look up healthily at Dictionary.com
1630s, from healthy + -ly (2).
healthy (adj.) Look up healthy at Dictionary.com
1550s, from health + -y (2). Slightly earlier in the same sense was healthsome (1530s). Related: 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]
heap (n.) Look up heap at Dictionary.com
Old English heap "pile, great number, multitude" (of things or persons), from West Germanic *haupaz (cognates: Old Saxon hop, Old Frisian hap, Middle Low German hupe, Dutch hoop, German Haufe "heap"), perhaps related to Old English heah "high." Slang meaning "old car" is attested from 1924. As a characteristic word in American Indian English speech, "a lot, a great deal," by 1832.
heap (v.) Look up heap at Dictionary.com
Old English heapian "collect, heap up, bring together;" from heap (n.). Related: Heaped; heaping. Compare Old High German houfon "to heap."
hear (v.) Look up hear at Dictionary.com
Old English heran (Anglian), (ge)hieran, hyran (West Saxon) "to hear, listen (to), obey, follow; accede to, grant; judge," from Proto-Germanic *hauzjan (cognates: Old Norse heyra, Old Frisian hora, Dutch horen, German hören, Gothic hausjan), perhaps from PIE *kous- "to hear" (see acoustic). The shift from *-z- to -r- is a regular feature in some Germanic languages.

For spelling, see head (n.); spelling distinction between hear and here developed 1200-1550. Old English also had the excellent adjective hiersum "ready to hear, obedient," literally "hear-some" with suffix from handsome, etc. Hear, hear! (1680s) was originally imperative, used as an exclamation to call attention to a speaker's words; now a general cheer of approval. Originally it was hear him!
heard Look up heard at Dictionary.com
past tense and past participle of hear, Old English herde.
hearer (n.) Look up hearer at Dictionary.com
mid-14c., agent noun from hear.
hearing (n.) Look up hearing at Dictionary.com
"perception by ear," early 13c., from present participle of hear. Meaning "a listening to evidence in a court of law" is from 1570s.
hearken (v.) Look up hearken at Dictionary.com
Old English heorcnian, 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; hearken likely is from influence of hear.
hearkening (n.) Look up hearkening at Dictionary.com
Old English heorcnunge "harkening, listening, power of hearing" (see hearken).
hearsay (n.) Look up hearsay at Dictionary.com
1530s, perhaps mid-15c., from phrase to hear say.
hearse (n.) Look up hearse at Dictionary.com
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," 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 so called because it resembled a harrow; hearse in its sense of "portcullis" is not attested in English before 15c. For spelling, see head. Sense extended to other temporary frameworks built over dead people, then to "vehicle for carrying a body," a sense first recorded 1640s.
heart (n.) Look up heart at Dictionary.com
Old English heorte "heart; breast, soul, spirit, will, desire; courage; mind, intellect," from Proto-Germanic *herton- (cognates: Old Saxon herta, Old Frisian herte, Old Norse hjarta, Dutch hart, Old High German herza, German Herz, Gothic hairto), from PIE *kerd- (1) "heart" (cognates: 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 remained when pronunciation shifted. Most of the figurative senses were present in Old English, including "intellect, memory," now only in by heart. Heart attack attested from 1875; heart disease is from 1864. The card game hearts is so called from 1886.
heart-rending (adj.) Look up heart-rending at Dictionary.com
also heartrending, heart rending, 1680s, from heart (n.) + present participle of rend (v.). Related: Heart-rendingly.
heart-throb (n.) Look up heart-throb at Dictionary.com
also heartthrob, 1839, from heart (n.) + throb (n.). Of persons who inspire romantic feelings, from 1928.
heartache (n.) Look up heartache at Dictionary.com
Old English heortece, in the sense of a physical pain; c. 1600 in sense of "anguish of mind;" from heart (n.) + ache (n.). Old English did, however, have heartsarnes "grief," literally "heart-soreness."
heartbeat (n.) Look up heartbeat at Dictionary.com
1850, from heart (n.) + beat (n.). From the beginning used as a figure for "a very brief time."
heartbreak (n.) Look up heartbreak at Dictionary.com
1570s, from heart (n.) + break (n.). Related: Heartbreaking.
heartbreaker (n.) Look up heartbreaker at Dictionary.com
1660s, originally "a fetching lock of hair;" of persons, from 1863; agent noun from heartbreak.
heartbroken (adj.) Look up heartbroken at Dictionary.com
1580s, present participle of heartbreak.
heartburn (n.) Look up heartburn at Dictionary.com
mid-13c., herte-brine "lust," later "heartburn, indigestion" (mid-15c.); also herte-brenning "anger, bitterness" (c. 1400), also "heartburn" (mid-15c.). See heart (n.) + burn (n.). Also see cardiac for confusion of "heart" and "stomach."
hearted (adj.) Look up hearted at Dictionary.com
now used only in combinations, meaning "at heart," since c. 1200, first attested in hard-hearted; see heart. Related: heartedly.
hearten (v.) Look up hearten at Dictionary.com
c. 1200, "to encourage," from heart + -en (1). A verb formed from figurative sense of heart. Related: Heartened; heartening.
heartfelt (adj.) Look up heartfelt at Dictionary.com
also heart-felt, 1734, from heart (n.) + past tense of feel (v.).
heartful (adj.) Look up heartful at Dictionary.com
"devout, earnest," mid-14c., from heart (n.) + -ful. Related: Heartfully.
hearth (n.) Look up hearth at Dictionary.com
Old English heorð "hearth, fire," in transferred use "house, home," from West Germanic *hertho "burning place" (cognates: Old Saxon and Old Frisian herth, Middle Dutch hert, Dutch haard, German Herd "floor, ground, fireplace"), from PIE *kerta-, from root *ker- "heat, fire" (see carbon).
heartily (adv.) Look up heartily at Dictionary.com
c. 1300, from hearty + -ly (2).
heartland (n.) Look up heartland at Dictionary.com
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.) Look up heartless at Dictionary.com
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" is not certainly attested before Shelley used it in 1816. Literal meaning "lacking a heart, lifeless" (mid-15c.) is rare. Related: Heartlessly; heartlessness.
heartsick (adj.) Look up heartsick at Dictionary.com
"despondent," late 14c., from heart (n.) + sick (adj.). Old English heortseoc meant "ill from heart disease."
heartstrings (n.) Look up heartstrings at Dictionary.com
late 15c., originally literal, in old anatomy theory "the tendons and nerves that brace the heart;" from heart (n.) + string (n.). Transferred and figurative sense from 1590s.
heartwarming (adj.) Look up heartwarming at Dictionary.com
1899, from heart (n.) + present participle of warm (v.).
hearty (adj.) Look up hearty at Dictionary.com
late 14c., "courageous; spirited, zealous;" also "loyal, faithful; sagacious, wise," from heart (n.) + -y (2). Related: Heartiness.
heat (n.) Look up heat at Dictionary.com
Old English hætu, hæto "heat, warmth; fervor ardor," from Proto-Germanic *haita- "heat" (cognates: 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" (see hot).

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 meaning "run given to a horse to prepare for a race" (1570s). This later expanded 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. Meaning "trouble with the police" attested by 1920. Heat wave "period of excessive hot weather" first attested 1890; earlier in reference to solar cycles.