Gringo does not come from green go home, and the dates rule it out

This is written to be used rather than admired. Each section below is a decision about the origin of the word gringo, and each one has a default.

The story and its variants

One version has Mexicans shouting at American soldiers in green uniforms to go home, with the chant compressing into a single word. Another involves a song beginning with the words green grow, sung by soldiers and misheard by locals.

A third relocates the whole episode to a different war, a different decade and sometimes a different country entirely. Multiple incompatible origin stories for the same word are close to conclusive evidence that all of them are later inventions. Each version is told with confident specificity, which is a general characteristic of stories that were made up to explain something.

The dating problem

The word is recorded in a Spanish dictionary published well before the conflict the story depends on. That dictionary defines it as referring to foreigners whose speech could not be understood, with no military or chromatic content. A word documented before the event that supposedly created it cannot have been created by that event.

This kind of dating check settles a great many folk etymologies immediately and requires no linguistic expertise. It also explains why specialists tend to be dismissive rather than curious about the soldier stories.

The likely derivation

The most commonly accepted account connects the word to the Spanish word for Greek, used in an expression equivalent to saying something is all Greek to me. Speaking in Greek was a standing idiom for unintelligible speech, and a word for a person who talks incomprehensibly follows naturally. The sound change from the word for Greek to the modern form is regular enough that linguists find it unremarkable.

The early definition, describing foreigners whose speech could not be followed, fits this derivation precisely. It is not certain, and etymologies of colloquial words rarely are, but it is supported rather than invented.

Why the uniform story is appealing

It supplies a specific historical grievance and turns a general word for foreigner into a record of a particular injustice. Stories that explain a word through a confrontation are dramatic and easy to remember, which is most of what a folk etymology needs.

The green uniform detail is also historically shaky, since the uniforms in question were not consistently that colour. A detail that is both essential to the story and factually wrong is a useful thing to look for.

The chant version additionally requires a phrase in English to be adopted by Spanish speakers, which is a strange direction for borrowing.

The wider category

Backronyms, where a word is explained as the initials of a phrase, are among the most common invented etymologies in any language. They are especially frequent for words with unclear origins, since a vacuum attracts an explanation.

The tell is usually that the phrase is in a different language from the word, or that it describes a modern situation. Genuine acronymic words exist and are usually recent and well documented, which is what distinguishes them. The general rule is that words older than the twentieth century are almost never acronyms.

Some of these are genuinely unsettled, and saying so is more honest than picking a side.

How to check one

Find the earliest recorded appearance in a historical dictionary of the relevant language, and compare it to the date of the story. Check whether the story exists in more than one version, since competing origins indicate later invention.

Tested properly, look for a plausible sound change from a known word, which is what most real etymologies consist of. Ask whether the explanation requires an undocumented event that nobody at the time thought worth recording. These four questions dispose of the overwhelming majority of colourful word origins in a couple of minutes.

The takeaway

The word was already in a dictionary before the war that supposedly invented it, which is usually where these stories end.

The satisfying version of a story is the one that travels, which is the whole problem.