Fervor is really just an intense passion heating up. Thus we shouldn’t be surprised that it comes from the Latin root fervere (“to boil”), from which we get the Spanish for the same (“to boil”), hervir.
The seemingly unrelated words are connected through the common transformation of Latin words beginning with an f- into an h- in Spanish, such as fig and higo, and fable and hablar.
Thus, the f-r-v of fervor maps to the h-r-v of hervir.
If he is fuming, he is smoking — literally. And it is, subtly, the same word in Spanish.
“To fume” comes from the Latin root fumus (“smoke”) from which we also get the common Spanish word for “smoke”, humo. But they don’t sound alike, so how are they related?
The Spanish humo is a great example of the pattern of the Initial F turning into an H in Spanish, alone among the languages of the world. Many Latin words that began with an F, and come to us in English through the Latinate F form, became the equivalent word but with an H- in Spanish. Take hermano and filial, for example. Or fact and hecho.
Other English words from the same root fumus include fumigation (ahhhh!) and the less common fetid. Fetid is a dirty, Shakespearean word, after all.
The Spanish hambre, for “hunger”, makes sense if you know two different patterns.
Firstly, the initial f-to-h pattern: words that began with an f- then a vowel in Latin tended to have the f- turned into an h- when Spanish evolved into Latin. Huir and Fugitive is another example of that pattern.
Secondly, the mn-to-mbr pattern: when the letters in Latin “m” and “n” appear together, often separated by a vowel, they usually became “mbr” as a unit in Spanish.
Thus the f-m-n of famine maps directly to the h-m-b-r of hambre.
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.
“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.