Etymology
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treacherous (adj.)
early 14c., from Old French trecheros, tricheros "deceitful" (12c.), from trecheor, tricheor "cheat, deceiver, liar, impostor, trickster," agent noun from trechier, trichier "to cheat, trick" (see trick (n.)). Figuratively, of things, from c. 1600. Related: Treacherously; treacherousness. Middle English had treacher "deceiver, cheat, traitor."
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delusory (adj.)

late 15c., "false, deceitful," from Latin delusor "a deceiver," from stem of deludere "to play false, mock, deceive" (see delude).

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Sinon 
name of the Greek who induced the Trojans to take the wooden horse into the city; hence "a deceiver by false tales."
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illusionist (n.)
"conjurer, magic act performer," 1840, from illusion + -ist. Earlier "one suffering from illusions" (1812). Middle English had illusor "deceiver, deluder."
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fraud (n.)

mid-14c., "criminal deception" (mid-13c. in Anglo-Latin); from Old French fraude "deception, fraud" (13c.), from Latin fraudem (nominative fraus) "a cheating, deceit," of persons "a cheater, deceiver," of uncertain origin. Connections have been proposed to Sanskrit dhruti- "deception; error."

Meaning "a fraudulent production, something intended to deceive" is from 1650s. The meaning "impostor, deceiver, pretender; humbug" is attested from 1850. Pious fraud (1560s) is properly "deception practiced for the sake of what is deemed a good purpose;" colloquially used as "person who talks piously but is not pious at heart."

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hornblende (n.)

common dark mineral, 1770, from German Hornblende, from horn "horn of an animal" (see horn (n.)) + blende (see blende).

The term "Hornblende" is an old German name for any dark, prismatic crystal found with metallic ores but containing no valuable metal (the word "Blende" indicates "a deceiver") [Herbert Bucksch, "Dictionary Geotechnical Engineering," 1995]

Related: Horneblendic.

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deceive (v.)

"mislead by false appearance or statement," c. 1300, from Old French decevoir "to deceive" (12c., Modern French décevoir), from Latin decipere "to ensnare, take in, beguile, cheat," from de "from" or pejorative (see de-) + combining form of capere "to take," from PIE root *kap- "to grasp." Related: Deceived; deceiver; deceiving.

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impostor (n.)

1580s, "swindler, cheat," from French imposteur (16c.), from Late Latin impostor "a deceiver," agent noun from impostus, contraction of impositus, past participle of imponere "place upon, impose upon, deceive," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + ponere "to put, place" (past participle positus; see position (n.)). Meaning "one who passes himself off as another" is from 1620s. Related: Impostrous. For a fem. form, Bacon uses French-based impostress (1610s) while Fuller, the church historian, uses Latinate impostrix (1650s).

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traitor (n.)

c. 1200, "one who betrays a trust or duty," from Old French traitor, traitre "traitor, villain, deceiver" (11c., Modern French traître), from Latin traditor "betrayer," literally "one who delivers," agent noun from stem of tradere "deliver, hand over," from trans- "over" (see trans-) + dare "to give" (from PIE root *do- "to give"). Originally usually with a suggestion of Judas Iscariot; especially of one false to his allegiance to a sovereign, government, or cause from late 15c. Compare treason, tradition.

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gab (v.)
"talk much," 1786, probably via Scottish and northern England dialect from earlier sense "speak foolishly; talk indiscreetly" (late 14c.), from gabben "to scoff, jeer; mock (someone), ridicule; reproach (oneself)," also "to lie to" (late 13c.), from a Scandinavian source, such as Old Norse gabba "to mock, make fun of," and probably in part from Old French gaber "to mock, jest; brag, boast," which, too, is from Scandinavian. Ultimately perhaps imitative (compare gabble, which might have shaded the sense of this word). Gabber was Middle English for "liar, deceiver; mocker." Related: Gabbed; gabbing.
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