What is a stool pigeon? Does it refer the bird’s habit of defecating on statues? Does it have something to do with furniture?
Stool does not refer to the piece of furniture or to dung. It is a variant of stale, meaning decoy. It comes from the Anglo-Norman estale or estal, a decoy bird used to entice a hawk to fly into a net. The French word probably originally derives from the Germanic steall meaning a place or standing position, or in this case a stationary bird. The root is also the source of the modern stall. From the c.1440 Anglo-Latin lexicon Promptorium Parvulorum Sive Clericorum:
Stale, of fowlynge or byrdys takynge, stacionaria.
(Stale, of fowling or birds taking, stacionaria.)
The word appears in American usage in the early 19th century, at first in the original sense of a decoy bird. From the town records of Huntington, N.Y. 1825:
No person be permitted to gun with macheanes or stools in sd. Town.
Within of years of this quote, the term stool pigeon appears, used in the sense of a decoy used to attract people. From the Workingman’s Gazette of Woodstock, Vermont, 1 December 1830:
A wag who keeps an oyster cellar in Newark advertises, among other things, “wildbirds domesticated and stool pigeons trained to catch voters for the next Presidency—warranted to suit either party.”
And Washington Irving’s Astoria of 1836 has this:
One man...was used like a “stool pigeon,” to decoy the others.
The decoy had changed to informer by 1849. From Banker’s Magazine of that year:
The senior high constable of Philadelphia...recollected that Harry White...who he had been lately using as a “stool pigeon,” or secret informer, had informed him...that “a big thing” was coming off shortly.
So a stool pigeon is a tool to catch criminals, or in modern parlance specifically an informer.
(Source: Oxford English Dictionary, 2nd Edition)
Copyright 1997-2015, by David Wilton