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.
One of our favorite patterns of sound change between English and Spanish is the sh/j shift: under the influence of arabic, many words that had a “s” or “sh” or “sy” or “ch” sound in Latin, started to be pronounced with the throat-clearing sound and written with a “j”. See sherry/jerez and chess/ajedrez or syrup/jarabe, for example.
Another example of this pattern is the Spanish word for “juice”, jugo. It comes from the Latin succus meaning, “juice” (particularly sap, or juice from plants).
From this Latin root succus we also get the English… suck.
Yes, if it sucks — it is juicy! Literally!
We can see the mapping in the s‑c to j‑g mapping. The “c” and “g” sounds are similar and often interchanged.
Interestingly, in Spain they do not say jugo to mean “juice”; instead, they say… suco. Suco, funnily enough, also comes from the same root of succus. It is just the variation that never underwent the arabic “j” transformation.
From the same root we also get the English succulent, although we do not get the superficially similar English juice, which comes from the Latin ius, meaning, “sauce.”
The Spanish for syrup, jarabe, comes from the same root as the English: the Persian/Arabic sharab, which means “a drink, or wine”.
The drastically different (at least superficially) words are explained by the sh- and related (such as, sy- ) sounds changing to the Arabic-sounding j- sound in Spanish — but not English.
Thus, the j‑r-b of jarabe maps to the sy-r‑p of syrup.
The Latin sounds for “sh” — and similar variations, like “ch” and “ss” — became a “j” sound in Spanish.
Thus, the English sherry is near identical to the Spanish jerez!
These sh/j sounds were often spelt with a “x” in old Spanish; and sherry itself is named after the town it first came from, Xeres, which is near Cordova.
Ajedrez (Spanish for “chess”) sounds nothing like the English chess, so they can’t be first cousins… right?
Wrong. The Spanish “j” sound — pronounced with an Arabic-ish throat-clearing sound — was originally pronounced with a “sh” or “ch” sound. The arabic influence changed the pronunciation to be closer to the arabic: see sherry/jerez, for example.
Ajedrez and Chess are another example of this same interesting pattern. Try to imagine the “j” in ajedrez with a ch- sound and you almost get chess.
Both, curiously, come from the same Sanskrit word for the game: chaturanga (so the English ch- is thus preserved closer to the original sound — English didn’t have the arabic influence that Spanish did). And these came to both languages via the Persian, chatrang. The traders and travelers, after all, are the ones who change languages.