A picayune was a Spanish coin, worth half a real. Its name derives from the French picaillon, which is itself from the Provençal picaioun, meaning "small coin". By extension, picayune can mean "trivial" or "of little value".
Aside from being used in Spanish territories, the picayune and other Spanish currency was used throughout the colonial U.S.. Spanish dollars were made legal tender in the United States by an act on February 9, 1793 until it was demonetized on February 21, 1857. The coin's name first appeared in Florida and Louisiana where its value was worth approximately six and a quarter cents, and whose name was sometimes used in place of the U.S. nickel.
A newspaper published in the New Orleans market, the Times-Picayune, is named after the picayune.