What's the difference between i.e. and e.g.?
masc. proper name, 1218, probably an anglicization of Old French Jacques (which was a diminutive of Latin Jacobus; see Jacob), but in English the name always has been associated with Johan, Jan "John," and some have argued that it is a native formation.
Alliterative coupling of Jack and Jill is from 15c. (Ienken and Iulyan). In England, applied familiarly or contemptuously to anybody (especially one of the lower classes) from late 14c. Later used especially of sailors (1650s; Jack-tar is from 1781). In U.S., as a generic name addressed to an unknown stranger, attested from 1889.
late 14c., jakke "a mechanical device," from the masc. name Jack. The proper name was used in Middle English for "any common fellow" (mid-14c.), and thereafter extended to various appliances replacing servants (1570s). Used generically of men (jack-of-all-trades, 1610s), male animals (1620s, see jackass, jackdaw, etc.), and male personifications (1520s, e.g. Jack Frost, 1826).
As the name of a device for pulling off boots, from 1670s. The jack in a pack of playing cards (1670s) is in German Bauer "peasant." Jack shit "nothing at all" is attested by 1968, U.S. slang. The plant jack-in-the-pulpit is attested by 1837. Jack the Ripper was active in London 1888. The jack of Union Jack is a nautical term for "small flag at the bow of a ship" (1630s).
1860, jack up "hoist, raise," American English, from the noun (see jack (n.)). Figurative sense "increase (prices, etc.)" is 1904, American English. Related: Jacked; jacking. Jack off (v.) "to masturbate" is attested from 1916, probably from jack (n.) in the sense of "penis."
1835, from earlier Lynch law (1811), likely named after William Lynch (1742-1820) of Pittsylvania, Virginia, who c.1780 led a vigilance committee to keep order there during the Revolution. Other sources trace the name to Charles Lynch (1736-1796) a Virginia magistrate who fined and imprisoned Tories in his district c.1782, but the connection to him is less likely. Originally any sort of summary justice, especially by flogging; narrowing of focus to "extralegal execution by hanging" is 20c. Lynch mob is attested from 1838. The surname is perhaps from Irish Loingseach "sailor." Cf. earlier Lydford law, from a place in Dartmoor, England, "where was held a Stannaries Court of summary jurisdiction" [Weekley], hence:
Lydford law: is to hang men first, and indite them afterwards. [Thomas Blount, "Glossographia," 1656]Related: Lynched; lynching.
[money sense probably fr the expression hard Jackson or hard Jackson money, referring to President Andrew Jackson and found by 1838; first verb sense perhaps related to mid-1800s British criminal slang jack, ''run away, escape,'' or perhaps by folk etymology fr jank, an echoic companion of jink; compare jink-jank with yin-yang and zig-zag; stealing sense probably fr hijack and related to carjacking]
Man; friend; fellow; mac •Used in addressing any man, whatever his name: Man, he's murder, Jack/ That supposed to be funny, jack? (1889+)
Nothing at all, zero; nada; jack shit: You don't know jack squat about going to college these days