The Spanish horno, for “oven,” sounds unrelated to any English counterpart.

But it is in fact a close cousin of furnace. Both come from the Latin formus, meaning “warn”.

How did such dissimilar words end up such close cousins?

Because most Latin words that began with an f- followed by a vowel ended up evolving in Spanish (alone among the romantic languages) into an h-. Thus the h-r-n of horno maps almost exactly to the f-r-n of furnace. In both cases, the original -m- evolved into an -n- in the root. But that is a very common transition too, with both sounds being very similar.

The Spanish for “beautiful”, hermosa, seems unrelated to the English for the same. Or is it?

Hermosa comes from the Latin for “beautiful” formosus.

We can see this pattern because it is an example of the Initial F to H pattern, where many Latin words that began with F- turned into H- in Spanish.

Ahhh, that makes sense: Formosa, in Argentina really means, “Beautiful”, and this also explains the Portuguese for beautiful (also formosa) as well: Portuguese never lost that initial F.

The Latin formosus itself comes from the root forma, meaning, well, “form”. So, beauty, itself, is just your pure form. At least in Spanish.

Herir (Spanish for, “to round”; most commonly heard in the form, “herido”, a wound) is a surprising cousin of… interfere. How so?

Interfere comes to us from the French entre– (“between”) and ferir (“to hit”). Interfering with something is really just hitting it right in the middle of it, breaking it up! Ferir comes from the Latin, for the same, Ferire.

Curiously, Ferire evolved into Spanish Herir — the Initial “F” turning into an “H”. It turns out, this is a common pattern as Latin evolved into Spanish — but in no other language! Just look at Filial and Hijo, or File and Hilo, or Fig and Higo.

Thus, the h-r of herir maps to the (int)-f-r of interfere.

Hierro is just Spanish for “iron”.

Here’s where it gets interesting: the Latin words beginning with f- generally turned into the silent h- in Spanish but not in the other Romantic languages, and thus hierro (from the Latin ferrum) is related to:

• Ferrocarril — Spanish for railroad. It maps almost perfectly to the English: ferro for ferrum, “iron”; and carril for road, way, or path (think of the common Spanish word for path or way, carrera).
• Ferrari — the luxury sports car from Italy, is named after their founding family’s last name. And that last name, in Italian, originally meant… iron-worker.

The Spanish “Huir” comes from the same Latin root as “fugitive”, “fugitivus”, meaning, “to flee”.

Pattern: Latin words that began with an ‘F’ tended to lose that initial ‘F’ sound and became silent (yet represented in writing with an ‘H’) as vulgar Latin turned into Spanish.

The Spanish for “son”, hijo, doesn’t sound like anything in English. But it is a close cousin of the English synonym for brotherliness: filial.

Both come from the Latin for “son,” filius. The transformation to Spanish came about through two interesting patterns: the initial f- in Latin usually turned into an h- in Spanish (such as, hacer and fact, or hablar and fable). The other pattern is less common: the -li- sound turned into a -j- sound – it’s just a less common sound! Thus the f-li maps to h-j almost exactly.

From the Latin filius, we get a few other English words, including: affiliate: an affiliate is, in a way, a child you rear!

From the same root we also get the English fetus, fecund and even feminine. These come, via the Latin filius, from the Proto-Indo-European root *dʰeh₁y-li-os, meaning, “sucker” — in the literal sense of, “one who sucks.” Children, indeed, are defined by their sucking their mothers; so your hijo is literally, “the one who sucks.” And, some might argue, even affiliates themselves usually do suck!

“Fig” comes from the Latin “Ficus” — obvious enough!

But, curiously, the Spanish word is “Higado”. Huh?

This is just a simple example of the Initial F to H pattern. In lots of Latin words, the first F became an H when Latin evolved into Spanish. Think fact/hecho or hablar/fable.

An easy way to figure out what an H- word in Spanish is: change the initial H to an F and see what English word sounds similar.