# The Spanish hiding in English

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Updated 2026-10-28 · HTML version: https://learnwithkin.com/spanish/hidden-cognates

> Many Spanish words that look nothing like English share a Latin root with an English word: *hecho* and fact, *hijo* and filial, *noche* and nocturnal. English borrowed its words from Latin in writing and kept their shape; Spanish inherited them in speech and changed them in regular ways. About a dozen changes do most of the work: *f* became *h*, *ct* became *ch*, a stressed *e* became *ie* and *o* became *ue*, and *pl*, *cl* and *fl* became *ll*.

**Interactive (on the web page).** Pick an English word, such as *fact*, and the Latin word behind it, *factum*, turns into Spanish one change at a time: *facto*, *fecho*, *hecho*. 46 words, from *fact* (*hecho*) and *ferrous* (*hierro*) to *flame* (*llama*) and *feminine* (*hembra*).

## Same word, two routes

English took words like *fact*, *nocturnal* and *ferrous* from Latin in writing, mostly through French and scholarship, so they kept their Latin shape. Spanish inherited the everyday Latin words underneath them, *factum*, *noctem* and *ferrum*, passed from speaker to speaker for well over a thousand years, and in speech words wear down in regular ways. So *factum* became *fact* in English and *hecho* in Spanish: the same word, taken by two different routes.

## A dozen changes do most of the work

The changes weren't random. A sound that changed in one word changed in nearly every word where it stood in the same place, which is why the same few patterns keep turning up. Pick one to see every word here it acted on.

**Interactive (on the web page).** The changes, each with the words it acted on. The ones worth knowing first: *f* → *h* (*hijo*, *hierro*, *humo*, *hablar*), *ct* → *ch* (*noche*, *leche*, *ocho*, *pecho*), *e* → *ie* and *o* → *ue* (*tierra*, *diente*, *puerta*, *nuevo*), and *pl*, *cl*, *fl* → *ll* (*lleno*, *llave*, *llama*, *llorar*).

## Try one yourself

Once you know the changes, you can run them yourself. Here's an English word, its Latin and the changes it went through. What did it become?

**Interactive (on the web page).** Guess the Spanish word from the English, the Latin and the changes: lactose (*leche*), implore (*llorar*), novel (*nuevo*), fume (*humo*), plenty (*lleno*), dental (*diente*), mortal (*muerte*), vital (*vida*).

## Using it when you read

- **Run the changes backwards.** Faced with a word you don't know, try *h* → *f*, *ch* → *ct*, *ie* → *e*, *ue* → *o*, *ll* → *pl*, and see if an English word appears. *Hierro* → ferro → ferrous, so it's iron.
- **Let the sentence check it.** A guess is a guess. If iron makes sense in the sentence, keep reading; if it doesn't, look the word up. Some relatives drifted apart in meaning, which is what [false friends](https://learnwithkin.com/spanish/false-friends) are about.
- **Start with the easy ones.** Most Latin words in Spanish didn't change much at all, and the endings tell you what they are: *nación*, *curiosidad*, *famoso*. [Spanish cognates](https://learnwithkin.com/spanish/cognates) has those patterns.

## How it works

The English word shares the Latin root. Sometimes it's the very same word (*factum*, fact), more often one built on it: nocturnal is from *nocturnalis*, built on *noctem*, and novel from *novellus*, built on *novum*. Each word starts from the Latin form Spanish grew from: usually the one used as an object (*noctem*, not *nox*), and sometimes the everyday spoken form (*lacte*, *scola*). The steps between are simplified. Some were written down (*fecho*, *fijo*, *fierro* and *fablar* are all Old Spanish), others are shorthand for changes that took centuries, and the order is the usual one, not a date. The changes also have exceptions: before *ct* and *li* a stressed *e* or *o* didn't break, which is why it's *noche* and *hoja*, not *nueche* and *hueja*. Only words that follow the changes are included (Penny, 2002).

## Questions

### Why does Spanish have h where English has f?

Because Spanish turned the *f* at the start of a Latin word into an *h*, which was once breathed and is now silent: *filium* became *hijo*, *ferrum* became *hierro*, *fumum* became *humo*. English borrowed words built on the same Latin roots, *f* and all: filial, ferrous and fume. The change didn't happen before *ue* or *r*, which is why Spanish still has *fuego*, *fuerte* and *frío*.

### Why do so many Spanish words have ie and ue?

A stressed short *e* in Latin broke into *ie* in Spanish, and a stressed short *o* into *ue*: *terra* became *tierra*, *porta* became *puerta*. That's also why some Spanish verbs change their stem when the stress falls on it: *poder* but *puedo*, *sentir* but *siento*.

### Is every Spanish h an old f?

No. Some come straight from a Latin *h*, as in *hora* and *humano*, and some were added in spelling, as in *huevo* (from *ovum*). An *h* followed by a vowel is still a good thing to try as an *f*: *hacer* is related to fact, *harina* to farina, *hoja* to foliage.

## Sources

- A History of the Spanish Language, 2nd edition. Ralph Penny, Cambridge University Press, 2002. https://doi.org/10.1017/CBO9780511992827
- Spanish etymologies. Wiktionary. https://en.wiktionary.org/wiki/Category:Spanish_terms_inherited_from_Latin

## Related

- [Spanish cognates](https://learnwithkin.com/spanish/cognates.md)
- [Spanish false friends](https://learnwithkin.com/spanish/false-friends.md)
- [How many words do you need to read a language?](https://learnwithkin.com/spanish/how-many-words.md)

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