Etymology
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stupidity (n.)
1540s, "want of intelligence," from Latin stupiditatem (nominative stupiditas) "dullness, stupidity, senselessness," from stupidus "confounded, amazed; dull, foolish" (see stupid). It also at various times meant "lack of feeling or emotion" (1560s); "stupor, numbness" (c. 1600).
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stolidity (n.)

1560s, from French stolidite and directly from Late Latin stoliditatem (nominative stoliditas) "dullness, obtuseness, stupidity," from Latin stolidus (see stolid).

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dumbness (n.)

"inability to speak," Middle English dombenesse, from Old English dumbnes; see dumb (adj.) + -ness. As "stupidity," by 1858.

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bluntness (n.)
late 15c., "stupidity," also "dullness of an edge, state or quality of being blunt," from blunt (adj.) + -ness. Meaning "rudeness" is from c. 1600.
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slack-jawed (adj.)
1882, "over-talkative," from slack-jaw (n.) "impertinent language" (1797), from slack (adj.) + jaw (n.). Meaning "open-mouthed and speechless" from astonishment, stupidity, etc., is from 1905.
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noob (n.)

c. 2000 in gamer slang, variant of newbie; often used interchangeably with it, but also often with a more derogatory shade of meaning; newbies owe their clueless behavior to lack of experience and are capable of improvement, while the fundamental characteristic of noobs is incorrigible obnoxiousness or stupidity.

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nicety (n.)

late 14c., nicete, "folly, stupidity," a sense now obsolete, from Old French niceté "foolishness, childishness, simplicity," from nice "silly" (see nice). It underwent a sense evolution parallel to that of nice, arriving at "minute, subtle point" 1580s and "exactitude, accuracy" in 1650s. Phrase to a nicety "exactly, with great exactness" is attested from 1795.

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folly (n.)
early 13c., "mental weakness; foolish behavior or character; unwise conduct" (in Middle English including wickedness, lewdness, madness), from Old French folie "folly, madness, stupidity" (12c.), from fol (see fool (n.)). From c. 1300 as "an example of foolishness;" sense of "costly structure considered to have shown folly in the builder" is attested from 1650s. But used much earlier, since Middle English, in place names, especially country estates, probably as a form of Old French folie in its meaning "delight." Related: Follies.
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mullet (n.2)

"hairstyle short the sides and long in back," 1996, perhaps from mullet-head "stupid, dull person" (1857). Mullet-head also was a name of a type of North American freshwater fish with a large, flat head (1866) with a reputation for stupidity. The term in reference to the haircut seems to have emerged into pop culture with the Beastie Boys song "Mullet Head."

#1 on the side and don't touch the back
#6 on the top and don't cut it wack, Jack
[Beastie Boys, "Mullet Head"]

As a surname, Mullet is attested from late 13c., thought to be a diminutive of Old French mul "mule." Compare also mallet-headed, in reference to the flat tops of chisels meant to be struck with a mallet.

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sapphire (n.)

precious stone, a blue-to-transparent variety of corundum next in hardness to diamond, mid-13c., saphyr, from Old French saphir (12c.) and directly from Latin sapphirus (source also of Spanish zafir, Italian zaffiro), from Greek sappheiros, name of a blue precious stone, from a Semitic source (compare Hebrew sappir "sapphire"), but according to OED probably not ultimately from Semitic.

Some linguists propose an origin in Sanskrit sanipriya, a dark precious stone (perhaps sapphire or emerald), literally "sacred to Saturn," from Sani "Saturn" + priyah "precious." The gem meant by the Greeks apparently was not the one now so called, but perhaps rather lapis lazuli, the modern sapphire perhaps being signified by Greek hyakinthos. In Renaissance lapidaries, it was said to cure anger and stupidity. As an adjective from early 15c. As a color, a deep brilliant or bright blue, by 1680s. Related: Sapphiric.

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