Etymology
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jockstrap (n.)
also jock-strap, "supporter of the male genital organs, used in sports," 1887, with strap (n.) + jock slang for "penis" c. 1650-c. 1850, probably one of the many colloquial uses of Jock (the northern and Scottish form of Jack), which was used generically for "common man" from c. 1500. Jockey-strap in the same sense is from 1890, with also an example from 1870 but the sense is uncertain.
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dibs (interj.)

children's word to express a claim on something, 1915, originally U.S., apparently from earlier senses "a portion or share" and "money" (early 19c. colloquial), probably a contraction of dibstone "a knuckle-bone or jack in a children's game" (1690s), in which the first element is of unknown origin. The game consisted of tossing up small pebbles or the knuckle-bones of a sheep and catching them alternately with the palm and the back of the hand.

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knave (n.)

late Old English cnafa "boy, male child; male servant," from Proto-Germanic *knabon- (source also of Old High German knabo "boy, youth, servant," German knabe "boy, lad"); it is also probably related to Old English cnapa "boy, youth, servant," Old Norse knapi "servant boy," Dutch knaap "a youth, servant," Middle High German knappe "a young squire," German Knappe "squire, shield-bearer." Original sense unknown; Klein suggests the prehistoric meaning might have been "stick, piece of wood." For pronunciation, see kn-.

Sense of "rogue, rascal" is first recorded c. 1200, presumably via sense evolution from "a menial" to "one of low birth," and the low character supposed to be characteristic of such a condition. But through Middle English it kept also its non-pejorative meaning, as in knave-child (Scottish knave-bairn) "male child." In playing cards, "the lowest court card," 1560s.

Previously, the English equivalent of the French valet was normally known as Knave, in the sense of 'serving-lad'. In the seventeenth century it came to be called Jack, from the name properly applied to the Knave of trumps at All Fours. All Fours being a low-class game, the use of 'Jack' for 'Knave' was long considered vulgar. ('He calls the Knaves Jacks!', remarks Estella contemptuously in Dickens's Great Expectations.) When indices came in, it was obviously preferable to use 'J' rather than 'Kn' to avoid confusion with 'K' for King. Jack has since become the normal title of the lowest court, though 'Knave' can still be heard. [David Parlett, "A History of Card Games," 1991]
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strait-jacket (n.)
also straitjacket, 1795 as a type of restraint for lunatics, from strait (adj.) + jacket (n.); earlier in same sense was strait-waistcoat (1753). As a verb from 1863. Related: Strait-jacketed.
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blue-jacket (n.)
also bluejacket, "a sailor" (as distinguished from a marine), 1830, from blue (adj.1) + jacket (n.).
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jackal (n.)
c. 1600, from French chacal, earlier jackal, from Turkish çakal, from Persian shaghal, from or cognate with Sanskrit srgala-s, literally "the howler." Figurative sense of "skulking henchman" is from the old belief that jackals stirred up game for lions.
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jacks (n.)
dexterity game played with a ball and small objects, 1900, from earlier jackstone "small round pebble used in games" (1792), which seems to be an alteration of checkstone (1745). The metal pieces with five arms or tines, made to be used in the game, are so called from 1908.
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schoolmarm (n.)

also school-marm, "female school teacher," 1834, American English colloquial, in the popular countrified humor writing of "Major Jack Downing" of Maine (Seba Smith); a variant of school-ma'am (1828), from school (n.1) + ma'am. See R. Used figuratively from 1887 in reference to patronizing and priggish instruction.

School-mistress "woman who teaches in a school" is attested from c. 1500 (mid-14c. as a surname, scole-maistres). School-dame (1650s) was generally "an old woman who keeps a school for small children."

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dolly (n.)

c. 1600, Dolly, a fem. nickname, extended form of Doll, short for Dorothy (see doll (n.)). In 17c. slang "a female pet or favorite." Modern slang sense of "young, attractive woman" is from 1906.

From 1790 as "a child's doll;" applied from 1792 to any contrivance fancied to resemble a dolly in some sense, especially "a small platform on rollers" (1901). Doesn't look like one to me, either, but that's what they say. Compare jack, jenny, jimmy, etc., generic proper names applied to various mechanical contrivances.

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ripper (n.)

1610s, "one who or that which rips," in any sense of that word, originally chiefly in technical use and slang, agent noun from rip (v.).

The meaning "killer who mutilates his victims" (1890) is from Jack the Ripper, the notorious London serial murderer of 1888-1891, whose nickname contains a pun on ripper in sense of "tool for ripping" old slates, etc. (1823) and the slang meaning "very efficient or excellent person or thing, a 'ripping' fellow" (1838), from ripping (q.v.) in the sense of "excellent, splendid."

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