Where did wop really come from? The best guess from etymologists is that the source is a southern Italian dialectal word, guappo or guappu, meaning “dandy” or “swaggerer.” That, in turn, is likely from the Spanish word guapo meaning “handsome” or “bold,” imported to Sicily when the island was occupied by Spain. Sicilian immigrants to the United States brought the swaggering word with them. It “connoted arrogance, bluster, and maleficence entwined,” wrote the music journalist Nick Tosches in his 2001 book Where Dead Voices Gather, in a historical exploration of the Italian-flavored pop-music genre once known as “wop songs.” Here is how Tosches describes (with some literary embellishment) the way that guappo and its variants became wop on American shores:

It was these Sicilian words that were commonly used to describe the work-bosses who lured their greenhorn paesani into servitude in New York City in the early years of the twentieth century. In New York and other American seaports, the lowly labor of the Italian immigrants’ servitude—the dockside toil and offal-hauling that others shunned—came to be called … guappu work; and eventually the laborer himself, and not the boss, was known as guappu. The peasant immigrants’ tendency to clip the final vowels from standard Italian and Sicilian—as in paesan’ for paesano—rendered guappu as guapp’, which was pronounced, more or less, as wop.

While there’s no hard evidence for the oral transformation of the word, the end result, wop, began making its appearance in written English in the early years of the 20th century. In 2010, on the American Dialect Society mailing list, word-researcher Douglas Wilson shared examples going back to 1906 in New York City newspapers. Here’s one:

There was a time, not very long ago, when you couldn’t find a Wop—that means an Italian in the latest downtown dialect—in Danny’s resort even by using a microscope. But to-day it’s different. The members of the Five Points gang, all dark skinned sons of Sicily, grew tired of flitting from place to place, with no set rendezvous for their nightly gatherings. A number of the Pointers used to frequent the place, and it wasn’t long before the entire gang became regulars. – The Sun, Nov. 18, 1906

The story of wop standing for “without papers” is of much more recent vintage. It started showing up in print in the early 1970s, at a time when Italian American identity politics was on the rise. But it likely circulated orally before that. In a 1971 journal article titled “A Study of Ethnic Slurs,” the folklorist Alan Dundes wrote:

One folk etymology for the word “wop,” a common term of disparagement for Americans of Italian descent, is that in the early 1920s many Italians tried to enter the United States illegally. These would-be immigrants were rounded up by U.S. officials and sent back to Italy with documents labelled W.O.P. which supposedly stood for “Without Papers” referring to the papers needed for legal immigration.

Later that year, the “without papers” story also appeared in the sports pages of the Tucson Daily Citizen, in a quote from Cleveland Indians manager Ken Aspromonte:

“If anyone called me a ‘wop’ I was furious and wanted to slug the guy right then and there,” Aspromonte said, “but then one day my grandfather explained the origin of the word. He told me that in the early 1900’s so many Italians were coming into the United States that many of them didn’t bother to get visas. When they’d arrive on Ellis Island and didn’t have papers with them the inspector would holler out, ‘Here’s another one, without papers.’ So somebody took the letters ‘W-O-P’ for ‘without papers’ and that’s how it got started,” Aspromonte said.

Also in 1971, the syndicated columnist Hy Gardner shared yet another folk etymology for wop. “‘Wop’ reverts to the turn of the century when millions of Calabrians and Sicilians came off their ships holding a slip of paper with the name of the foreman they had been assigned to,” Gardner wrote. “U.S. immigration officials rubberstamped the papers ‘W.O.P.’—meaning ‘without passport.’”