Etymology
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jack-in-the-box (n.)
also jack-in-a-box, 1560s, a name for a sharp or cheat, "who deceived tradesmen by substituting empty boxes for others full of money" [Robert Nares, "A Glossary of Words, Phrases, Names, and Allusions," London, 1905]. See Jack + box (n.1). As a type of toy involving a figure on a spring inside a box, it is attested by 1702. Also it has been used variously to mean "peddler who sells wares from a temporary stall" (1690s), "an unborn child," a type of gambling game, a hermit crab, a large wooden male screw, the sacrament, and various mechanical devices.
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brother-in-law (n.)
"brother of one's husband or wife," also "brother of one's sister's husband," c. 1300; also brother in law; see brother + in-law. In Arabic, Urdu, Swahili, etc., brother-in-law, when addressed to a male who is not a brother-in-law, is an extreme insult, with implications of "I slept with your sister."
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mother-in-law (n.)

late 14c., moder-in-laue, "mother of one's spouse," from mother (n.1) + in-law. Also in early use, "stepmother." In British slang c. 1884, mother-in-law was said to mean "a mixture of ales old and bitter."

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hole-in-the-wall (n.)
"small and unpretentious place," 1816, perhaps recalling the hole in the wall that was a public house name in England from at least 1690s. "Generally it is believed to refer to some snug corner, perhaps near the town walls," but the common story was that it referred to "the hole made in the wall of the debtors' or other prisons, through which the poor prisoners received the money, broken meat, or other donations of the charitably inclined" [Jacob Larwood and John Camden Hotten, "The History of Signboards: From the Earliest Times to the Present Day," 1867]. Mid-19c. it was the name of the private liquor bar attached to the U.S. Congress.
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inwork (v.)
1680s, from in (adv.) + work (v.).
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incohesion (n.)
1781; see in- (1) "not, opposite of" + cohesion.
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