The Grammarphobia Blog

You dirty, yellow-bellied rat

Q: A post about the word “rat” as it relates to despicable, disloyal, or deceitful people would be interesting, don’t you think?

A: When “rat” showed up in Old English (as ræt) it meant the rodent that we’re all familiar with. It didn’t refer to human rats until hundreds of years later. Here’s the story.

The earliest example in the Oxford English Dictionary is from a Latin-Old English translation (“Raturus, ræt”) in the Antwerp-London Glossaries, a collection of 11th-century manuscripts derived from earlier texts.

Similar words for the rodent appeared in other Germanic languages (Old Saxon ratta, Old Swedish rotta, Old High German rato, etc.), as well as in medieval Latin and Romance languages.

“The word was probably spread with the reintroduction of rats to Northern Europe during the Viking Age,” the OED notes. (The Norse seafarers raided and traded from the 8th to the 11th centuries.)

The relationship between the Germanic and Latin terms for “rat” is murky. As the OED explains, “It is uncertain whether the Latin and Romance words are cognate with the Germanic words, or whether they were borrowed from Germanic, or vice versa.” (Cognates are related linguistically.)

The dictionary notes that there’s no written evidence for any of the Latin or Romance words “before the end of the first millennium.”

The word’s “ultimate origin is uncertain,” the OED says, but it offers a creepy suggestion: the usage is “perhaps imitative of the sound of gnawing.”

English speakers began using the word “rat” for people in the 16th century, at first for someone who was dishonest, contemptible, or worthless, especially in a romantic relationship.

The first example in the OED is from A Chronicle of All the Noble Emperours of the Romaines (1571), by Richard Reynolds:

“He was a scourge to the Enuches, and lasciuious Courtiars, he called them the moathes and rattes of Princes Courtes.” (“Moath” was used figuratively for a person dangerously drawn to temptation, as a moth to a flame.)

In the 17th century, a “rat” came to mean a disorderly person—at first a rowdy arrested for drunkenness, and later any disruptive or troublesome person.

The OED has a questionable citation from 1607. The first definite example for the new sense is from Life and Death of Mrs. Mary Frith (1662), an anonymous biography of a cutpurse, or pickpocket:

“A Shoomaker … being then Constable … was pleased for all my faire Words and Account to send me to the Counter for a Rat.” (A “counter” was a prison attached to a court. We’ve expanded the Oxford citation to add context.)

In the 18th century, according to the OED, “rat” took on the political sense of someone “who deserts his or her party, side, or cause; a person who puts personal considerations before political principles, departs radically from the official party line, or adopts the political beliefs of a rival party.”

The dictionary attributes this figurative sense of the word to “the belief that rats leave a ship about to sink or a house about to fall down.”

The earliest Oxford example for this sense is from “A Dialogue Between X, Y, and Z,” by Benjamin Franklin, published in the Dec. 18, 1755, issue of the Pennsylvania Gazette:

“Z. For my Part, I am no Coward; but hang me if I’ll fight to save the Quakers. X. That is to say, you won’t pump Ship, because ’twill save the Rats,—as well as yourself.”

In the early 19th century, “rat” adopted the slang sense of a “person who gives information, esp. of an incriminating nature, on another person to the police or other authority, an informer.”

The OED’s first example is from The Fudge Family in Paris (1818), an epistolary novel in verse, by Thomas Moore: “Give me the useful peaching Rat; / Not things as mute as Punch, when bought.”

(Around this same time, “stool pigeon” also became a slang term for an informer, as we wrote in 2008.)

Soon afterward, “rat” also came to mean a “person who refuses to strike, or takes the place of a striking worker” as well as “a non-union worker” or “a person who works for lower wages than the usual or trade union rate.”

Here’s an example from the March 6, 1824, issue of the Microscope, a weekly in Albany, NY: “Loren … Webster, chief ink-dauber in a rat-printing office at the west. Ralph Walby, nothing at all but a rat-printer.”

We should mention here that James Cagney never used the exact phrase “you dirty rat” despite all the Cagney imitators using it on YouTube. The closest he came was “that dirty, double-crossing rat” in Blonde Crazy (1931) and “you dirty, yellow-bellied rat” in Taxi! (1932).

There are several other less common meanings of “rat” in the human sense, but we’ll skip them and end this post with the old expression “to smell a rat”—that is, to suspect deception or foul play.

The first OED citation is from The Image of Ipocrysy, a poem by John Skelton from around 1540: “Yf they smell a ratt, / They grisely chide and chatt.”

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