Gig is an interesting word with a variety of senses, not all etymologically related.
The oldest sense is that of a top or other whirling object. Originally whirligig, the origin is unknown but is probably echoic. From Promptorium Parvulorum Sive Clericorum, Lexicon Anglo-Latinum Princeps, c.1440:
Whyrlegyge, chyldys game, giraculum.
(Whirligig, child’s game, giraculum.)1
This sense of top is the source of some other senses, such as a giddy or flighty person, fun, merriment, and a whim.
The sense of a light, two-wheeled carriage is transference from the earlier sense. The motion of the carriage and its tendency to upset are not unlike that of a top. From Geoffrey Gambado’s An Academy for Grown Horsemen, 1791:
Airing en famille, in a gig, accompanied with a husband and three children.
Also related is the sense of gig meaning a ship’s boat. From John Wolcott’s 1790 Advice to the Future Laureat:
That by its painter drags the Gig or Yawl.2
Gig can also mean a spear or harpoon, and it is a verb meaning to spear or stab, as in the Texas A&M collegiate cheer, Gig’em Aggies. From Robert Beverley’s 1722 History of the Present State of Virginia:
At each End of the Canoe stands an Indian, with a Gig, or pointed Spear, setting the Canoe forward with the Butt-end of the Spear, as gently as he can, by that Means, stealing upon the Fish, without any Noise.3
This sense originally comes from the Spanish word for harpoon, fisga. An alternate spelling is fizgig and the word is also folk-etymologized as fishgig. From a 1565 account by J. Sparke in Richard Hakluyt’s 1582 Diuers Voyages Touching the Discouerie of America:
Those bonitos...being galled by a fisgig did follow our shippe...500 leagues.4
This brings us to the most common sense in use today, that of a musician’s engagement or job. But the origin is not in music. The musical sense stems from a sense of a business affair or event. From McClure’s Magazine of February 1907:
What’s this gig about militia?
A year later, the sense meaning a non-musical job appears. From Helen Green’s 1908 Maison De Shine:
“What’s your game?” the Property Man’s tone was rather unpleasant. “I’m champion paper-tearer of the West,” said Charlie. “I pass...what kind o’ gig is that?”
The musical sense dates to 1926. From R.S. Gold’s Jazz Talk of that year:
One popular “gig” band makes use of a nicely printed booklet.
Finally, there is a U.S. Army slang sense meaning a punishment or demerit. This comes from a more general sense of gig meaning a goad or gibe. This comes from the sense of a spear, to be goaded is not unlike being skewered. From George Ade’s 1901 Modern Fables:
The Old Gentleman was very rough on Wallie. He gave him the Gig at every opportunity, for he had no sympathy for Puppy Love and he hated a Dude.
By 1930, this general sense had specialized into the military sense of a demerit. From Dale O. Smith’s Cradle of Valor of that year:
I’m riding well with only six gigs so far this month.5
2OED2, gig, n.2, <http://dictionary.oed.com/cgi/entry/50094458>.
3OED2, gig, n.4, <http://dictionary.oed.com/cgi/entry/50094460>.
4OED2, fizgig, fisgig, <http://dictionary.oed.com/cgi/entry/50085434>.
5Historical Dictionary of American Slang, v. 1, A-G, edited by Jonathan Lighter (New York: Random House, 1994), 890-91.
Copyright 1997-2015, by David Wilton