Etymology
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lightness (n.)
"quality of having little weight," late Old English lihtnesse, from light (adj.1) + -ness.
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levitation (n.)
1660s, noun of action from Latin levitas "lightness" (see levitate) + -ion.
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levitate (v.)
1670s, "to rise by virtue of lightness" (intransitive), from Latin levitas "lightness," on the model of gravitate (compare levity). Transitive sense of "raise (a person) into the air, cause to become buoyant" (1870s) is mainly from spiritualism. Related: Levitated; levitating.
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ballon (n.)
"smoothness in dancing, lightness of step," 1830, from French ballon, literally "balloon" (see balloon (n.)).
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fairness (n.)
Old English fægernes "beauty;" see fair (adj.) + -ness. Meaning "even-handedness, impartiality" is from mid-15c. Meaning "lightness of complexion" is from 1590s.
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buoyancy (n.)
1713, "relative lightness, quality of floating on water or other liquid," from buoyant + -cy. Figurative sense "cheerfulness, hopefulness" (of spirits, etc.) is from 1819. Meaning "power of supporting a body so that it floats" is from 1831.
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levity (n.)
1560s, "want of seriousness, frivolity," from French levite, from Latin levitatem (nominative levitas) "lightness," literal and figurative; "light-mindedness, frivolity," from levis "light" in weight, from PIE root *legwh- "not heavy, having little weight." In old science (16c.-17c.), the name of a force or property of physical bodies, the opposite of gravity, causing them to tend to rise.
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chiffon (n.)

1765, "feminine finery, something used by women purely for adornment," from French chiffon (17c.), diminutive of chiffe "a rag, piece of cloth" (17c.), which is of unknown origin, perhaps a variant of English chip (n.1) or one of its Germanic cousins. Klein suggests Arabic. Meaning "sheer silk fabric, thin gauze" is from 1890. Extension to pastry is attested by 1929, probably on the notion of "lightness."

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facility (n.)

early 15c., "gentleness, lightness," from Old French facilité "easiness, ease," from Latin facilitatem (nominative facilitas) "easiness, ease, fluency, willingness," from facilis "easy to do," from facere "to do" (from PIE root *dhe- "to set, put"). First in a medical book:

If it be nede forto smyte [the head] wiþ a malle, be it done with esynez or facilite [transl. Guy de Chauliac's "Grande Chirurgie"]

Its sense in English expanded to "opportunity" (1510s), to "aptitude, ease, quality of being easily done" (1530s). Meaning "place for doing something" which makes the word so beloved of journalists and fuzzy writers, first recorded 1872, via notion of "physical means by which (something) can be easily done."

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iamb (n.)

in prosody, a foot of two syllables, the first short or unaccented, the second long or accented, 1842, from French iambe (16c.) or directly from Latin iambus "an iambic foot; an iambic poem," from Greek iambos "metrical foot of one unaccented followed by one accented syllable" (see iambic). Iambus itself was used in English in this sense from 1580s. In Greek, the measure was said to have been first used by satiric writers.

[The Iambus] is formed constantly by the proper accentuation of familiar, but dignified, conversational language, either in Greek or English : it is the dramatic metre in both, and in English, the Epic also. When the softened or passionate syllables of Italian replace the Latin resoluteness, it enters the measure of Dante, with a peculiar quietness and lightness of accent which distinguish it, there, wholly from the Greek and English Iambus. [Ruskin, "Elements of English Prosody, for use in St. George's Schools," 1880]
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