Etymology
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Hades 

"god of the dead in Greek mythology;" also the name of his realm, the abode of the dead spirits, 1590s, from Greek Haidēs, in Homer the name of the god of the underworld, son of Kronos and Rhea, brother of Zeus and Poseidon. His name is of unknown origin. Perhaps literally "the invisible" [Watkins], from privative prefix a- + idein "to see" (from PIE root *weid- "to see"). The name of the god was extended in later Greek writing to his kingdom, also "the grave, death." Related: Hadal (adj.), 1964; Hadean.

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blight (n.)
1610s, origin obscure; according to OED it emerged into literary speech from the talk of gardeners and farmers. It is perhaps from Old English blæce, blæcðu, a scrofulous skin condition and/or from Old Norse blikna "become pale" (from the group including bleach, bleak, etc.). Used in a general way of agricultural diseases, sometimes with suggestion of "invisible baleful influence;" hence figurative sense of "anything which withers hopes or prospects or checks prosperity" (1660s). Compare slang blighter. Urban blight "condition of disrepair and poverty in a previously thriving part of a city" attested by 1935.
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*wer- (1)

Proto-Indo-European root meaning "to raise, lift, hold suspended." 

It forms all or part of: aerate; aeration; aerial; aero-; aerobics; aerophyte; aerosol; air (n.1) "invisible gases that surround the earth;" airy; aorta; anaerobic; aria; arterial; arterio-; arteriosclerosis; arteriole; artery; aura; malaria; meteor

It is the hypothetical source of/evidence for its existence is provided by: Greek aerein "to lift, raise up;" Lithuanian svarus "heavy," sverti "to lift, weigh;" Old English swar, Old Norse svarr, Old High German swar, German schwer "heavy."

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voice (n.)

late 13c., "sound made by the human mouth," from Old French voiz "voice, speech; word, saying, rumor, report" (Modern French voix), from Latin vocem (nominative vox) "voice, sound, utterance, cry, call, speech, sentence, language, word" (source also of Italian voce, Spanish voz), related to vocare "to call" (from PIE root *wekw- "to speak").

Replaced Old English stefn "voice," from Proto-Germanic *stemno, from PIE *stomen- (see stoma). Meaning "ability in a singer" is first attested c. 1600. Meaning "expression of feeling, etc." (in reference to groups of people, etc., such as Voice of America) is recorded from late 14c. Meaning "invisible spirit or force that directs or suggests," (especially in the context of insanity, as in hear voices in (one's) head, is from 1911.

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dern (adj.)

"secret, hidden," from Old English derne (West Saxon dierne) "concealed, secret, dark," from West Germanic *darnjaz (source also of Old Saxon derni, Old Frisian dern "concealed, dark," Old High German tarni "secret, concealed, veiled"), related to dark (adj.).

Archaic or poetic only after 16c., it was important and productive in Middle English, with extended senses of "secluded; profound, mysterious; stealthy, deceptive; private, confidential." Dern love was "secret or illicit love; a mistress."

As a verb, meaning "to conceal," it was from Old English diernan "to hide." Compare Old Saxon dernian, Old High German tarnjan "to conceal, hide;" German Tarnkappe, Tarnhelm "magical cap or helmet which turns the wearer invisible or allows him to assume any form." French ternir "to tarnish, to dull" apparently is from Germanic.

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ceiling (n.)

mid-14c., celynge, "act of paneling a room," noun formed (with -ing) from Middle English verb ceil "put a cover or ceiling over," later "cover (walls) with wainscoting, panels, etc." (early 15c.); from Old French celer "to conceal," also "cover with paneling" (12c.), from Latin celare "to hide" (from PIE root *kel- (1) "to cover, conceal, save"). Probably influenced by Latin caelum "heaven, sky" (see celestial).

Extended to the paneling itself from late 14c., then to lath-and-plaster work.  The meaning "interior overhead surface of a room" is attested by 1530s; by late 19c. the meaning "wainscoting" was only in provincial English. Figurative sense "upper limit" is from 1934. Colloquial figurative phrase hit the ceiling "lose one's temper, get explosively angry" attested by 1908; earlier it meant "to fail" (by 1900, originally U.S. college slang). Glass ceiling in the figurative sense of "invisible barrier that prevents women from advancing" in management, etc., is attested from 1988.

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influence (n.)

late 14c., an astrological term, "streaming ethereal power from the stars when in certain positions, acting upon character or destiny of men," from Old French influence "emanation from the stars that acts upon one's character and destiny" (13c.), also "a flow of water, a flowing in," from Medieval Latin influentia "a flowing in" (also used in the astrological sense), from Latin influentem (nominative influens), present participle of influere "to flow into, stream in, pour in," from in- "into, in, on, upon" (from PIE root *en "in") + fluere "to flow" (see fluent).

The range of senses in Middle English was non-personal, in reference to any outflowing of energy that produces effect, of fluid or vaporous substance as well as immaterial or unobservable forces. Meaning "exertion of unseen influence by persons" is from 1580s (a sense already in Medieval Latin, for instance Aquinas); meaning "capacity for producing effects by insensible or invisible means" is from 1650s. Under the influence (of alcohol, etc.) "drunk" first attested 1866.

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panel (n.)

early 14c., "a piece of cloth," especially a rectangular piece, from Old French panel "piece of cloth, piece, saddle cushion" (Modern French panneau), from Vulgar Latin *pannellus, diminutive of Latin pannus "piece of cloth" (see pane).

Anglo-French legalese sense of "piece of parchment (cloth) listing the names of those summoned to serve upon a jury" led by late 14c. to the meaning "a jury selected for a trial." General sense of "persons called on to advise, judge, discuss," etc. is from 1570s. Sense of "more or less distinct part of the surface of a wall, door, etc." is recorded from c. 1600.

Panel-house (said to be from 1840s; popular from 1870s) was old slang for a disreputable place (typically a bordello) with panneled rooms. At least one panel could be slid back to allow for thefts from customers and other cheats. Hence panel-thief, panel-game, etc.

The requisites for a "panel house" in the proper sense, are,—a crafty, cunning street walker; a not less cunning and at the same time sturdy scoundrel—known in the slang of the business as a "Badger," and a room prepared specially for the purpose by having a small invisible opening, generally a noiselessly opening panel in the partition or entrance door, by which access to the place can be had from an adjoining room. These three requisites obtained, it becomes the duty of the panel-thief to find the fourth in any "greenhorn" that can be picked up on the streets and induced to come into the apartment. ["The Dark Side of New York Life and its Criminal Classes," 1873]
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air (n.1)

c. 1300, "invisible gases that surround the earth," from Old French air "atmosphere, breeze, weather" (12c.), from Latin aer "air, lower atmosphere, sky," from Greek aēr (genitive aeros) "mist, haze, clouds," later "atmosphere" (perhaps related to aenai "to blow, breathe"), which is of unknown origin. It is possibly from a PIE *awer- and thus related to aeirein "to raise" and arteria "windpipe, artery" (see aorta) on notion of "lifting, suspended, that which rises," but this has phonetic difficulties.

In Homer mostly "thick air, mist;" later "air" as one of the four elements. Words for "air" in Indo-European languages tend to be associated with wind, brightness, sky. In English, air replaced native lyft, luft (see loft (n.)). In old chemistry, air (with a qualifying adjective) was used of any gas.

To be in the air "in general awareness" is from 1875; up in the air "uncertain, doubtful" is from 1752. To build castles in the air "entertain visionary schemes that have no practical foundation" is from 1590s (in 17c. English had airmonger "one preoccupied with visionary projects"). Broadcasting sense (as in on the air, airplay) first recorded 1927. To give (someone) the air "dismiss" is from 1900. Air pollution is attested by 1870. Air guitar is by 1983. Air traffic controller is from 1956.

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constellation (n.)

early 14c., constellacioun, "position of a planet in the zodiac;" late 14c., "one of the recognized star patterns handed down from antiquity" (in the zodiac or not), from Old French constellacion "constellation, conjuncture (of planets)" and directly from Late Latin constellationem (nominative constellatio) "a collection of stars," especially as supposed to exert influence on human affairs," from constellatus "set with stars," from assimilated form of Latin com "with, together" (see con-) + past participle of stellare "to shine," from stella "star" (from PIE root *ster- (2) "star").

The oldest sense is astrological, of the position of planets ("stars") relative to the zodiac signs on a given day, usually the day of one's birth, as a determiner of one's character. "I folwed ay myn inclinacioun/By vertu of my constillacioun" (Chaucer, "Wife's Prologue," c. 1386). In modern use "a group of fixed stars to which a definite name has been given but does not form part of another named group (compare asterism). Figuratively, "any assemblage of a brilliant or distinguished character"(1630s).

The classical northern constellations probably were formed in prehistoric Mesopotamia; the Greeks likely picked them up c. 500 B.C.E., and Claudius Ptolemy (c. 90-c. 168) of Alexandria codified 48 of them, all still current, in his "Almagest" (2c.). The canonical list was expanded from 16c. as Europeans explored southern regions whose stars were invisible from Alexandria and as astronomers filled in the dimmer regions between the established figures, so that by the late 19c. as many as 109 constellations were shown on maps. The modern roster was set at 88 by the International Astronomical Union in 1922.

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