False Friend : A word that looks the same in two different languages but means two different things.
In Chamorro, siempre means "surely, certainly, definitely." But in Spanish it means "always."
If a Spaniard asks if you will be going to the market today, and you answer "Siempre," the Spaniard will think you always go to the market, and you will have thought you were telling the Spaniard that you were certainly going to the market that day.
"Always" was the original meaning of siempre in Chamorro, since we borrowed the word from the Spaniards. Consult the older Chamorro dictionaries and you will see this. But it doesn't take much analysis to see how "always" evolved into "certainly." If something always happens, it is certain that it will happen.
Our mañaina used different words to say "surely, certainly, definitely." They also used Spanish words to express these ideas. Seguro was one. Even today we can say seguro when we want to say "surely, definitely, certainly."
Another word for "certainly" was fiho. We got that from the Spanish fijo, which means "definite, permanent, stable." The meaning of fiho changed and it now means "often" in Chamorro, although one can still use the original meaning as in, "fiho na hinasso," or "unchanging thinking or mentality."
Sen magahet literally means "very true" but it can also be used to express the idea that something is certain or definite. Sen magahet is also purely indigenous Chamorro; not an ounce of Spanish there.
We can also still say siempre when we want to say "always," although most of us will say "todo i tiempo," which is still borrowing from Spanish.
The changing meanings of siempre and fiho, which changed just within the space of a hundred years, show that languages evolve, even without outside influence. There is no language that is fiho throughout its entire history, even if there is no colonizer who introduces changes.