Continuing the recent saber and sage conversation…
Quizás (Spanish for “perhaps”) comes from the Latin qui sapi — literally, “Who knows?”. The sapi in that phrase is from the Latin for “to know”, sapere, from which root we get the English… savvy. Someone who is savvy just knows a lot about the subject!
The final -s of quizás maps to the first s- of savvy. And the -p- in sapere, although vanished from quizás, maps to the -vv- in savvy.

Thursday and Jueves, like the other days of the week, come from the Germanic and Latin names for the same God: the King of the Gods, the God known as “Zeus” to the Greeks, and sometimes as “Jupiter.”
The Latin sounds for “sh” — and similar variations, like “ch” and “ss” — became a “j” sound in Spanish.