Etymology
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curdle (v.)

1630s (earlier crudle, 1580s), "to thicken, cause to congeal, change or form into curd" (transitive), frequentative of curd (v.) "to make into curd" (late 14c., from the noun; see curd). Intransitive sense of "to coagulate, thicken" is from c. 1600. To curdle (one's) blood, in the figurative sense of "inspire horror" is from c. 1600. Related: Curdled (1580s); curdling (1690s, almost always of blood and in the figurative sense).

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gruesome (adj.)
1560s, with -some (1) + grue, from Middle English gruen "feel horror, shudder" (c. 1300); not recorded in Old English or Norse, possibly from Middle Dutch gruwen or Middle Low German gruwen "shudder with fear" (compare German grausam "cruel"), or from a Scandinavian source (such as Danish grusom "cruel," grue "to dread," though others hold that these are Low German loan-words). One of the many Scottish words popularized in England by Scott's novels. Related: Gruesomely; gruesomeness.
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electrocution (n.)

"execution by electricity," 1889, American English; noun of action from electrocute. Meaning "any death by electricity" is from 1897.

Electrocution, unless better performed than in the first instance, is a retrograde step rather than the contrary. The preliminary arrangements: the shaving of the head, the cutting of the clothing, the strapping in a chair, add much to the horror of the occasion. It is safe to say that electrocution is not the coming method of execution. [The Medical Era, vol. vii, no. 9, Sept. 1890]
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barmaid (n.)

"woman who tends a bar," 1650s, from bar (n.2) + maid.

The one employment from which Americans turn their faces in righteous horror is that of the barmaid. They consider it a degrading position, and can not understand how English people reconcile with their professions of Christianity the barbarous practice of exposing women to the atmosphere of a liquor bar at a railway station, where they must often run the gauntlet of the insolent attentions of the "half-intoxicated masher," endure vulgar familiarity, and overhear low conversation. [Emily Faithfull, "Three Visits to America," 1884]
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abomination (n.)
Origin and meaning of abomination

early 14c., "abominable thing or action;" late 14c., "feeling of disgust, hatred, loathing," from Old French abominacion "abomination, horror, repugnance, disgust" (13c.), from Latin abominationem (nominative abominatio) "abomination," noun of action from past-participle stem of abominari "shun as an ill omen," from ab "off, away from" (see ab-) + omin-, stem of omen (see omen).

In biblical use, often "that which is ceremonially impure." The meaning was intensified by folk etymology derivation from Latin ab homine "away from man" (thus "beastly"); Wyclif and Chaucer both have abhominacioun, and abhominable was mocked by Shakespeare in "Love's Labour's Lost."

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phobia (n.)

"irrational fear, horror, or aversion; fear of an imaginary evil or undue fear of a real one," 1786, perhaps based on a similar use in French, abstracted from compounds in -phobia, the word-forming element from Greek phobos "fear, panic fear, terror, outward show of fear; object of fear or terror," originally "flight" (still the only sense in Homer), but it became the common word for "fear" via the notion of "panic flight" (compare phobein "put to flight; frighten"), from PIE root *bhegw- "to run" (source also of Lithuanian bėgu, bėgti "to flee;" Old Church Slavonic begu "flight," bezati "to flee, run;" Old Norse bekkr "a stream").

The psychological sense of "an abnormal or irrational fear" is attested by 1895. Hence also Phobos as the name of the inner satellite of Mars (discovered 1877) and named for Phobos, the personification of fear, in mythology a companion of Ares.

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waltz (n.)

round dance performed to music in triple time, extraordinarily popular as a fashionable dance from late 18c. to late 19c., the dance itself probably of Bohemian origin, 1779 (walse, in a translation of "Die Leiden des jungen Werthers" from a French translation, which has walse), from German Waltzer, from walzen "to roll, dance," from Old High German walzan "to turn, roll," from Proto-Germanic *walt- (cognate with Old Norse velta), from PIE root *wel- (3) "to turn, revolve." Described in 1825 as "a riotous and indecent German dance" [Walter Hamilton, "A Hand-Book or Concise Dictionary of Terms Used in the Arts and Sciences"].

The music struck up a beautiful air, and the dancers advanced a few steps, when suddenly, to my no small horror and amazement, the gentlemen seized the ladies round the waist, and all, as if intoxicated by this novel juxtaposition, began to whirl about the room, like a company of Bacchanalians dancing round a statue of the jolly god. "A waltz!" exclaimed I, inexpressibly shocked, "have I lived to see Scotch women waltz?" [The Edinburgh Magazine, April 1820]
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monster (n.)
Origin and meaning of monster

early 14c., monstre, "malformed animal or human, creature afflicted with a birth defect," from Old French monstre, mostre "monster, monstrosity" (12c.), and directly from Latin monstrum "divine omen (especially one indicating misfortune), portent, sign; abnormal shape; monster, monstrosity," figuratively "repulsive character, object of dread, awful deed, abomination," a derivative of monere "to remind, bring to (one's) recollection, tell (of); admonish, advise, warn, instruct, teach," from PIE *moneie- "to make think of, remind," suffixed (causative) form of root *men- (1) "to think."

Abnormal or prodigious animals were regarded as signs or omens of impending evil. Extended by late 14c. to fabulous animals composed of parts of creatures (centaur, griffin, etc.). Meaning "animal of vast size" is from 1520s; sense of "person of inhuman cruelty or wickedness, person regarded with horror because of moral deformity" is from 1550s. As an adjective, "of extraordinary size," from 1837. In Old English, the monster Grendel was an aglæca, a word related to aglæc "calamity, terror, distress, oppression." Monster movie "movie featuring a monster as a leading element," is by 1958 (monster film is from 1941).

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concentration (n.)

1630s, "action of bringing to a center, act of collecting or combining into or about a central point," noun of action from concentrate (v.). Meaning "a mass so collected" is from 1670s; that of "voluntary continuous focusing of mental activity" is from 1825, in phrenology.

Concentration camp is from 1901, originally "compound for noncombatants in a war zone," a controversial idea in the second Boer War (1899-1902). The term emerged with a bad odor.

The concentration camp has now definitely taken its place side by side with the Black Hole of Calcutta as one of those names of horror at which humanity will never cease to shudder. [The Review of Reviews, London, March 1902]

But it also was used 1902 in reference to then-current U.S. policies in the Philippines, and retroactively in reference to Spanish policies in Cuba during the 1896-98 insurrection there. The phrase was used domestically in the U.S. during the Spanish-American war but only in reference to designated rendezvous points for troops headed overseas. In reference to prisons for dissidents and minorities in Nazi Germany from 1934, in Soviet Russia from 1935. 

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bug (n.)

"insect, beetle," 1620s (earliest reference is to bedbugs), of unknown origin, probably (but not certainly) from or influenced by Middle English bugge "something frightening, scarecrow" (late 14c.), a meaning obsolete since the "insect" sense arose except in bugbear (1570s) and bugaboo (q.v.).

Probably connected with Scottish bogill "goblin, bugbear," or obsolete Welsh bwg "ghost, goblin" (compare Welsh bwgwl "threat," earlier "fear," Middle Irish bocanách "supernatural being"). Some speculate that these words are from a root meaning "goat" (see buck (n.1)) and represent originally a goat-like spectre. Compare also bogey (n.1) and Puck. Middle English Compendium compares Low German bögge, böggel-mann "goblin." Perhaps influenced in meaning by Old English -budda used in compounds for "beetle" (compare Low German budde "louse, grub," Middle Low German buddech "thick, swollen").

The name of bug is given in a secondary sense to insects considered as an object of disgust and horror, and in modern English is appropriated to the noisome inhabitants of our beds, but in America is used as the general appellation of the beetle tribe .... A similar application of the word signifying an object dread to creeping things is very common. [Hensleigh Wedgwood, "A Dictionary of English Etymology," 1859]

Meaning "defect in a machine" (1889) may have been coined c. 1878 by Thomas Edison (perhaps with the notion of an insect getting into the works). Meaning "person obsessed by an idea" (as in firebug "arsonist") is from 1841, perhaps from notion of persistence. Sense of "microbe, germ" is from 1919. Bugs "crazy" is from c. 1900. Bug juice as a slang name for drink is from 1869, originally "bad whiskey." The 1811 slang dictionary has bug-hunter "an upholsterer." Bug-word "word or words meant to irritate and vex" is from 1560s.

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