jag

Etymology 1

The noun is from late Middle English jagge, the verb is from jaggen.

noun

1. A sharp projection.
   The thick black cloud was cleft, and still / The Moon was at its side; / Like waters shot from some high crag, / The lightning fell with never a jag, / A river steep and wide. 1798, Samuel Taylor Coleridge, The Rime of the Ancient Mariner, lines 323–7
   The especial beauty of London is the Thames, and the Thames is so wonderful because the mist is always changing its shapes and colours, always making its light mysterious, and building palaces of cloud out of mere Parliament Houses with their jags and turrets. 1909, Arthur Symons, London: A Book of Aspects, self-published, page 3
   Even if you hadn’t been drowned, you would have been smashed to pieces by the terrible weight of water against the countless jags of rock. 1956, C. S. Lewis, chapter 16, in The Last Battle, Collins, published 1998
2. A part broken off; a fragment.
   some Jaggs will ſuffice to be recited 1693, John Hacket, Scrinia Reserata
   I depart as air .... I shake my white locks at the runway sun, / I effuse my flesh in eddies and drift it in lacy jags. 1855, Walt Whitman, “Song of Myself”, in Leaves of Grass, page 56
3. A flap, a tear in a clothing
4. (botany) A cleft or division.
5. (Scotland) A medical injection, a jab.
6. (Western Pennsylvania, dialectal) A thorn from a bush (see jaggerbush).
7. (Western Pennsylvania, dialectal, derogatory) Ellipsis of jagoff.: An irritating, inept, or repugnant person.

verb

1. To cut unevenly.
2. (Western Pennsylvania) To tease.

Etymology 2

Circa 1597; originally "load of broom or furze", variant of British English dialectal chag (“tree branch; branch of broom or furze”), from Old English ċeacga (“broom, furze”), from Proto-Germanic *kagô (compare dialectal German Kag (“stump, cabbage, stalk”), Swedish dialect kage (“stumps”), Norwegian dialect kage (“low bush”), of unknown origin.

noun

1. Enough liquor to make a person noticeably drunk; a skinful.
2. A binge or period of overindulgence; a spree.
   Consider, the pessimists argue, the vast number of plays which it is only possible to sit through with the assistance of what Ella Wheeler Wilcox would call a mild jag. 1919 August, P. G. Wodehouse, “Prohibition and the Drama”, in Vanity Fair, page 21
   ‘People who spend their money for second-hand sex jags are as nervous as dowagers who can't find the rest-room.’ 1939, Raymond Chandler, The Big Sleep, Penguin, published 2011, page 88
3. A fit, spell, outburst.
   Of course she did not lose her sense of humor (not necessarily to be confused with her laughing fits, which are crying jags turned inside out according to the shrinks). 1985, Peter De Vries, chapter 9, in The Prick of Noon, Penguin, page 165
   Miles had a cold, he always had a cold, it went unnoticed, went without saying, he had coughing jags and slightly woozy eyes, completely unremarked by people who knew him […] 1997, Don DeLillo, Underworld, Simon & Schuster, published 2007, Part 4, Chapter 1, p. 396
4. A one-horse cart load, or, in modern times, a truck load, of hay or wood.
5. (Scotland, archaic) A leather bag or wallet; (in the plural) saddlebags.