As a language learner, it’s inevitable that you’ll eventually encounter the premise that cognates are your friends. You don’t have to re-learn every word from scratch if you can already tell what a lot of them mean, the idea goes. But what is a cognate, exactly? Are all foreign language words that sound like their English counterparts there to provide shortcuts to fluency, or are some of them setting you up for a dangerous booby trap?

Judging from this small assortment of benign English words that sound dirty in other languages, it’s obviously not enough for two words to sound alike. In the world of language learning, a familiar face can be an enemy in disguise.

Here’s what it takes to be a cognate, how to skillfully use them to your advantage, and what to remember when you invariably get them mixed up.

What Is A Cognate?

Put simply, a cognate is a word that sounds similar to a word in another language, shares the same meaning and has a common linguistic ancestor that they both stemmed from.

The word cognate comes from the Latin word cognatus, which means “related by blood.” It can also refer to people, groups of people, and figurative concepts like “cognate disciplines,” but in linguistics, it specifically points to words that share this special relationship.

In other words, a cognate isn’t just a random doppelgänger who kind of looks like you — it’s your second cousin.

An example of this is the word “problem” in English, which translates to el problema in Spanish. They sound alike, they mean the same thing, and they both come from the Ancient Greek πρόβλημα (próblēma), which became the Latin problema.

An example of languages that share many cognates are Romance languages like Spanish, French, Italian and Portuguese. They all descend from the same ancestral language, which is Latin.

Cognates Are Your Friends!

As an aspiring speaker of German or Italian (or any other language that shares a lot of cognates with English), cognates are here to help you.

One of the things we often recommend learners do, especially when they’re just starting out, is to begin with the easy part. You likely already know more than you think you do! Rather than discourage yourself right out the gate by starting with the most difficult vocabulary, it’s helpful and motivating to begin with the words you already kind of know.

Cognates also leave behind important historical breadcrumbs. Researchers from the United Kingdom were able to discover what the oldest words in the world were, and therefore determine that many disparate languages likely evolved from a single proto-Eurasiatic language, by studying cognates. By looking at the frequency of cognates across seven language groups, they determined that at least 23 words many languages share in common are likely nearly 15,000 years old, having survived since the end of the last ice age.

…Until They’re Not

There’s an estimate that about 90 percent of Spanish words that look like English words are actual cognates. If you want to rest on the assumption that every familiar-sounding Spanish word means what you think it means, the odds are in your favor!

However, there’s still the problem of that remaining 10 percent. Though minuscule, it’s in this percentile that you find false friends like embarazada, which doesn’t mean “embarrassed,” but rather “pregnant.”

Sometimes, similar-sounding words mean very different things, and this is why you have to tread carefully. For example, a gift is a nice thing in English, while Gift in German means “poison.” In Swedish, Norwegian and Danish, it means “married” — there’s probably a good joke in there somewhere.

A false cognate is a word that appears to be another word’s counterpart in a different language, but in fact doesn’t derive from the same linguistic ancestor. For example, the word “pie” in English comes from the Latin word pia, which means “pastry.” The Spanish pie means “foot,” coming from the Latin pes.

This is not to be confused with “false friend.” A false friend can be a true cognate in the sense that two words come from the same mother, but they’ve grown apart so much that they no longer mean the same thing. The English “embarrassed” via the Spanish embarazada is a good example of this.

Some words can also share similar meanings even though they come from different roots. These are considered false cognates.

Truly, though, there’s no easy rule of thumb that’s going to help you tell them all apart. Until you have every word committed to memory (which, in all likelihood, you won’t), the best thing you can do is give each potential cognate the benefit of the doubt, and be prepared to be hilariously wrong from time to time.