Cuñado, Spanish for “brother-in-law,” comes from the Latin cognatus, from which we get the near-identical English cognate. How can two words so similar mean something so different?
The Latin root cognatus itself came from the roots com- (meaning “together”) and gnasci (meaning “to be born”); thus, literally, “born together.” So, two words that are cognates are — etymologically-speaking — words that are born together. And brothers-in-law are two men who are not brothers but were, in effect at least, born together as well.
Note also that this is an example of the pattern whereby Latin words with a ‑gn- generally became an ñ in Spanish. Thus the c‑gn‑t of cognate maps to the c‑ñ-d of cuñado.
Luchar, Spanish for “to fight”, doesn’t sound like its cousin reluctant — although of course everyone is reluctant to fight. But the relationship is closer than it seems.
Reluctant comes from the Latin roots re- (“against”) and luctari (“to fight”). Reluctance is to fight against what should be done — literally.
From luctari, we also get the Spanish for exactly the same, “to fight.”
But they don’t sound similar. How did luchar evolve?
Interestingly, in most Latin words that had a ‑ct- sound, this ‑ct- sound evolved into ‑ch- as Latin evolved into Spanish. Think about night/noche and eight/octagon. The same pattern explains luctari turning into luchar.
We see this relationship clearly with the l‑ct to l‑ch mapping between the two.
The Spanish huso (“spindle” — what Cinderella uses to weave!) comes from the Latin for the same: fusus.
The transition is clear when we remember that the initial F in Latin usually turned into an “h” in Spanish: fig vs higo, for example. Or herir vs interfere, for another.
From the same Latin root fusus, we also get the English… fuse. Why? Well, look at the shape: an old-school spindle looks like a big fuse!
Thus, we can see the f‑s of fuse map clearly to the h‑s of huso.
Otoño doesn’t sound much like its English translation, fall (the season). But if we think of the less common synonym, Autumn, then the pattern becomes a bit clearer.
Both come from the Latin for the same, Autumnus. But Latin words with an m‑n sound usually became an ñ sound in Spanish. Think of damn and daño, for example. So the a‑t-m‑n of autumn maps to the o‑t-ñ of otoño!
The Spanish eje for “axle” comes from the Latin for the same, axis. The English axle comes from the same common ancestor as the Latin axis, the proto-indo-european root *aks- also meaning the same.
The Spanish eje is easy to understand if we remember that most of the x/sh/ch sounds in Latin and the ancient languages became the throat-clearing ‑j- sound in Spanish. Thus, the e‑j of eje maps to the a‑x of axle pretty clearly.
It’s interesting how such a simple word has remained mostly unchanged for tens of thousands of years. Perhaps, the axle is one of the most fundamental discoveries in human history. It is, after all, what led to the wheel, which led to… civilization.