Online Etymology Dictionary

Hilda: fem. proper name, German, literally "battle-maid," from fem. of Old High German hild "war, battle," from Proto-Germanic *hildiz "battle," from PIE *keldh-, from root *kel- "to strike, cut."
Hildebrand: masc. proper name, Old High German Hildibrand, literally "battle-sword;" for first element see Hilda; for second element see brand.
Hildegard: fem. proper name, Old High German Hildegard, literally "protecting battle-maid;" for first element see Hilda; for second element see yard (n.1).
hill (n.): Old English hyll "hill," from Proto-Germanic *hulni- (cf. Middle Dutch hille, Low German hull "hill," Old Norse hallr "stone," Gothic hallus "rock," Old Norse holmr "islet in a bay," Old English holm "rising land, island"), from PIE root *kel- "to rise, be elevated, be prominent" (cf. Sanskrit kutam "top, skull;" Latin collis "hill," columna "projecting object," culmen "top, summit," cellere "raise," celsus "high;" Greek kolonos "hill," kolophon "summit;" Lithuanian kalnas "mountain," kalnelis "hill," kelti "raise"). Formerly including mountains, now usually confined to heights under 2,000 feet.
In Great Britain heights under 2,000 feet are generally called hills; 'mountain' being confined to the greater elevations of the Lake District, of North Wales, and of the Scottish Highlands; but, in India, ranges of 5,000 and even 10,000 feet are commonly called 'hills,' in contrast with the Himalaya Mountains, many peaks of which rise beyond 20,000 feet. [OED]

The term mountain is very loosely used. It commonly means any unusual elevation. In New England and central New York, elevations of from one to two thousand feet are called hills, but on the plains of Texas, a hill of a few hundred feet is called a mountain. [Ralph S. Tarr, "Elementary Geology," Macmillan, 1903]

Despite the differences in defining mountain systems, Penck (1896), Supan (1911) and Obst (1914) agreed that the distinction between hills, mountains, and mountain systems according to areal extent or height is not a suitable classification. ["Geographic Information Science and Mountain Geomorphology," 2004]
Phrase over the hill "past one's prime" is first recorded 1950.
hillbilly (n.): "southern Appalachian U.S. resident," by 1892, from hill + masc. proper name Billy/Billie.
Then again, I do not think It will do so well. I would hate to see some old railroad man come here and take my job, and then, I don t think It is right to hire some Hill Billy and give him the same right as I just because he was hired the same time I was. ["The Railroad Trainmen's Journal," vol. IX, July 1892]

In short, a Hill-Billie is a free and untrammelled white citizen of Alabama, who lives in the hills, has no means to speak of, dresses as he can, talks as he pleases, drinks whiskey when he gets it, and fires of his revolver as the fancy takes him. ["New York Journal," April 23, 1900]
In reference to a type of folk music, first attested 1924.
Hillel: masc. proper name, from Hebrew, literally "he praised."
hillock (n.): late 14c., hilloc "small hill" (c.1200 as a surname), from hill + Middle English diminutive suffix -oc.
hillside (n.): late 14c., from hill + side (n.).
hilltop (n.): c.1400, from hill + top (n.).
hilly (adj.): late 14c., from hill + -y (2).
hilt (n.): Old English hilt "hilt, handle of a sword or dagger," from Proto-Germanic *helt (cf. Old Norse hjalt, Old High German helza "hilt," Old Saxon helta "oar handle"), perhaps from PIE *kel- "to strike." Formerly also used in plural in same sense as singular.
hilum (n.): Latin, literally "little thing, shred, trifle." Related: Hilar.
him (pron.): Old English him, originally dative masculine and neuter of he; beginning 10c. it replaced hine as masculine accusative, a regional process completed by 15c. The dative roots of the -m ending are retained in German (ihm) and Dutch (hem). Hine persists, barely, as the southern England dialectal 'un, 'n for "him."
Himalaya: from Sanskrit himalayah, literally "abode of snow," from hima "snow" (see hibernation) + alaya "abode." Related: Himalayas; Himalayan.
himself (pron.): Old English him selfum, from him, dative/accusative personal pronoun, + self, here used as an inflected adjective.
hin (pron.): Old English hine, accusative of he; replaced by dative him in early Middle English; cognate with German ihn. Surviving somewhat in s.w. English and Kentish dialect.
hincty (adj.): "conceited," by 1924 in U.S. black slang. Cf. obsolete Scottish hichty (c.1500), considered an alteration of height-y.
hind (adj.): c.1300, "rear, back," perhaps a back-formation from Old English behindan "back, behind," used as adverb and preposition, or from or influenced by Old English hindan (adv.) "from behind," from Proto-Germanic *hind- "behind" (cognate with Gothic hindan (prep.) "on that side of, beyond, behind;" German hinten "behind"), of unknown origin. Possibly influenced by Middle English hiner (adv.) "back, rear."
hind (n.): "female deer," Old English hind, from Proto-Germanic *hinthjo- (cf. Old Norse hind, Dutch hinde, Old High German hinta, German Hinde "hind") perhaps from PIE *kemti-, from root *kem- "hornless" (cf. Greek kemas, Lithuanian smulas "young deer, gazelle").
hinder (v.): Old English hindrian "to harm, injure, impair, check, repress," from Proto-Germanic *hinderojanan (cf. Old Norse hindra, Dutch hinderen, Old High German hintaron, German hindern "to keep back"), from a root meaning "on that side of, behind" (cf. hind (adj.)); thus the ground sense is "to put or keep back," though this sense in English is recorded only from late 14c. Related: Hindered; hindering.
hinder (adj,): "situated in the rear, toward the back," late 14c., probably from Old English hinder (adv.) "behind, back, afterward," but treated as a comparative of hind (adj.). Related to Old High German hintar, German hinter, Gothic hindar "behind." Middle English had hinderhede, literally "hinder-hood; posterity in time, inferiority in rank;" and hinderling "person fallen from moral or social respectability, wretch."
hinderance (n.): early form of hindrance.
hindermost: late 14c., hyndermest; see hinder (adj.) + -most.
Hindi: 1825 as an adjective; 1880 as a language name, from Hind "India" (see Hindu) + -i, suffix expressing relationship.
hindmost (adj.): late 14c., from hind (adj.) + -most.
Thra. What, if a toy take 'em i' the heels now, and they run all away, and cry, 'The devil take the hindmost'?
Dion. Then the same devil take the foremost too, and souse him for his breakfast! [Beaumont & Fletcher, "Philaster," Act V, Sc. 2, 1611]
Hindoo: old anglicized form of Hindu (q.v.).
hindrance (n.): mid-15c., a hybrid from hindren, from same root as hinder (v.), on model of French-derived words in -ance.
hindsight (n.): by 1841, "backsight of a firearm," from hind (adj.) + sight. Meaning "seeing what has happened" is attested by 1862, American English, (in proverbial "If our foresight was as good as our hindsight, it would be an easy matter to get rich"), probably a formation on the model of foresight.
Hindu: 1660s, from Persian Hindu (adjective and noun) "Indian," from Hind "India," from Sanskrit sindhu "river," specifically the Indus; hence "region of the Indus," gradually extended across northern India. The Hindu Kush mountain range is said to mean literally "Indian killer," and was said to have been the name given by the Persians to a pass where their Indian slaves had perished in winter, but this is likely folk etymology.
Hinduism (n.): blanket term for "polytheism of India," 1829, from Hindu + -ism.
Hindustan: 1610s, from Persian, literally "country of the Hindus;" see Hindu + -stan.
hine: see hin.
hinge (n.): c.1300, "the axis of the earth;" late 14c. as "movable joint of a gate or door," not found in Old English, cognate with Middle Dutch henghe "hook, handle," Middle Low German henge "hinge," from Proto-Germanic *hanhan (transitive), *hangen (intransitive), from PIE *konk- "to hang" (see hang (v.)). The notion is the thing from which a door hangs.
hinge (v.): c.1600, "to bend," from hinge (n.). Meaning "turn on, depend" is from 1719. Related: Hinged; hinging.
hinny (n.): "offspring of a stallion and a she-ass," 1680s, from Latin hinnus, from Greek innos, ginnos, of unknown origin.
hinny (v.): "to neigh," c.1400, of imitative origin.
hint (n.): c.1600, apparently from obsolete hent, from Middle English hinten "to tell, inform" (c.1400), from Old English hentan "to seize," from Proto-Germanic *hantijanan (cf. Gothic hinþan "to seize"), related to hunt (v.). Modern sense and spelling first attested in Shakespeare.
hint (v.): 1640s, from hint (n.). Related: Hinted; hinting.
hinterland (n.): 1890, from German Hinterland, from hinter "behind" (see hinder (adj.)) + Land "land" (see land (n.)).
hip (n.1): "part of the body where pelvis and thigh join," Old English hype "hip," from Proto-Germanic *hupiz (cf. Dutch heup, German Hüfte, Gothic hups "hip"), from PIE *qeub- "to bend." Hip of a roof is from late 17c.
hip (n.2): "seed pod" (especially of wild rose), Old English heope, hiope "seed vessel of the wild rose," from Proto-Germanic *hiup- (cf. dialectal Norwegian hjupa, Old Saxon hiopo, Dutch joop, Old High German hiafo, dialectal German Hiefe, Old English hiopa "briar, bramble").
hip (adj.): "informed," 1904, apparently originally in black slang, probably a variant of hep (1), with which it is identical in sense, though it is recorded four years earlier.
hip (interjection): exclamation used to introduce a united cheer (cf. hip-hip-hurrah), 1827, earlier hep, cf. German hepp, to animals a cry to attack game, to mobs a cry to attack Jews (see hep (2)); perhaps a natural sound (cf. Latin eho, heus).
hip hop: also hip-hop, music style, first recorded 1982. Reduplication with vowel variation (e.g. tip-top, sing-song); OED reports use of hip hop with a sense of “successive hopping motion” dating back to 1670s. The term in its modern sense comes from its use in the early rap lyrics of the genre, notably Grandmaster Flash and the Furious Five and The Sugarhill Gang in "Rapper's Delight."
hiphuggers (n.): also hip-huggers, "low-rise pants or skirt," 1966, from hip + agent noun from hug. So called because they are slung from the hips, not the waist. Earlier as the name of a cut of women's swimsuit (1963).
hipped (adj.): "having hips," c.1500, past participle adjective; see hip (n.1)). In architecture from 1823.
hippie (n.): c.1965, American English (Haight-Ashbury slang); earlier hippie, 1953, was a usually disparaging variant of hipster (1941) "person who is keenly aware of the new and stylish," from hip "up-to-date" (see hip (adj.)).
hippish (adj.): "somewhat depressed," 1706, from hip (n.) "melancholy," variant of hyp, short for hypochondria.
hippo (n.): short for hippopotamus, attested from 1872.
hippo-: before vowels, hipp-, word-forming element meaning "horse," from Greek hippo-, from hippos "horse," from PIE *ekwo- (see equine).