The Spanish for “foam”, espuma, comes from the Latin for the same: spuma. And this Latin comes from the Proto-Indo-European root *(s)poi-moi from which we also get the English… foam.
How so? Because the PIE root p- very consistently became an f- as it evolved into German then English, but this transformation never happened when it became Latin and then Spanish. Note words like foot/pie and father/padre.
Thus the f‑m of foam maps to the (s)-p‑m of espuma very clearly!
Ah, one of our all-time favorite patterns and examples: leche, the common Spanish word meaning, “milk.”
Leche is a first cousin of the English lactose via a very interesting pattern: the ‑ct- to ‑ch- pattern.
Both come from the same Latin root, lactatio (literally, “suckling.”) The ‑ct- in that root remained unchanged as it entered English (because it entered via the sophisticated French) but that sound almost always turned into a ‑ch- sound as Latin evolved into Spanish. Thus the l‑ct maps to the l‑ch almost exactly.
Many other awesome words follow the same pattern: think octagon/ocho, for example. Some more coming up soon (or see the pattern page linked below).
The Latin words that began with “cl” changed, pretty consistently, to “ll” as Latin changed into Spanish.
Today’s example of this: the Latin word for “key” was clavis. This became the modern Spanish word for “key”, llave.
There are, however, a few interesting other descendants of clavis, and thus distant relatives of llave. They include:
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 correr, “to run” seems completely unrelated to the English horse. Looks can be deceiving.
Correr comes from the Latin for the same, currere. Currere, in turn, comes from the Proto-Indo-European root *kurs, which also means, “to run” — just like horse does! Both have the same common ancestor.
The weird thing is: how did the PIE *kurs turn into horse, they sound so different.
The explanation is that, in the Germanic languages like English, the k- sound turned into the h- sound. But in Spanish, the original k- sound remained, although usually written with a c-.
This explains many parallel words that have c- and h- sounds that map to each other between Spanish and English, like heart/corazon and head/cabeza.