Today’s is a good one!
The Spanish caro (simply, “expensive”) has a fun provenance: from the ancient (pre-Latin) Proto-Indo-European root karo– that meant… whore. Yes, the ancient word karo turned into the almost-as-ancient Latin word carus meaning “expensive,” from which we get the modern Spanish word caro, still meaning “expensive.”
So the prostitutes of the ancient world, apparently, weren’t cheap!
Interestingly, we can even see a linguistic connection between the words. The k- sound in Proto-Indo-European stayed the same sound as it evolved into Latin and then Spanish (although usually written with a c-); but as Proto-Indo-European evolved simultaneously into ancient German and then into English, that k- sound became the silent or almost-silent h- or wh-. Think when and cuando, for example. So, we can see therefore that the c-r of caro maps to the wh-r of whore.
The funniest part, however, is that the ancient Latin carus, for expensive, as Latin evolved into French, turned into the French… cher, for “dear”: in the sense of, “My dear friend!”. The exact opposite of a whore! Thus, in French, prostitute became expensive which became that which is dear to you!
The Spanish pegar (“to paste”) comes from the Latin pix, meaning “tar.” That makes sense: “paste” looks like just a more diluated “tar.”
But pix itself comes from the Proto-Indo-European root pei(e), which meant, fat — think of animal fat, for example. It makes sense that this word evolved into a word meaning “tar”: that’s a bit what animal fat looks like.
From this same root pei(e), we get a few notable English words:
Estafa, Spanish for “to rip off” in the sense of taking advantage of someone or stealing, comes from the Italian staffa, which means “stirrup”. This change of meaning came about because it was common, back in the day, for people to borrow a horse… and then never return it.
The Italian staffa itself comes from the Proto-Indo-European root stebh, which meant “to fasten, or place firmly” from which we get the English… staff. A staff, after all, is a stick that helps you fasten something into place! At least, it used to.
From the same PIE root, we get other English words including step, stump, stamp and… Stephen.
The st-f root is visible in both estafa and staff.
The Spanish aprovecharse (“to take advantage of,” in a good way) comes from the Latin ad– (“towards”) and profectus (“progress, success.”)
From the same root profectus, we get the English… profit.
We can see the root pr-v of aprovecharse mapping to the pr-f of profit. And how do you make a profit if not, taking advantage of the opportunities in front of you?
Yerno (Spanish for “son-in-law”) at first sounds like nothing in English.
But let’s look closer! The g- and y- sounds are often mixed up between languages and even regions that speak the same language; in fact, the Old English g- transformed itself into a y- over time (compare the German gestern with the English yesterday, for example). And the n-r sound not uncommonly swaps to become an r-n sound, the two are easily mixed up, especially in slurred speech.
Thus, the bizarre-sounding y-r-n root of yerno maps to the g-n-r root of generic (Maybe sons-in-laws are more generic in Spanish cultures than English ones?) as well as genus (which lost the final r-) — yes, genus as in Latin and now scientific classification of your spot in the universe! The son-in-law, I guess, is destined to be the son-in-law as his lot-in-life.