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!
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 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.
The Spanish hilo (cord; thread; string) comes from the Latin for the same, filum. The words sound very different, until we remember that, words in Latin that began with a f- tended to change to h- in Spanish: hijo/filium, and hoja/foliage, for example. Now the hilo/filum make sense!
Interestingly, however, from that same Latin root filum, we get various English words that also quietly show they are descendants of the word for cord or thread. Including:
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 a “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.