The Spanish for “cow” vaca, comes from the Latin vacca, meaning the same. From that same root, we get the English.… vaccine/em.

Huh? How?

Interestingly, the first, umm, vaccine, was to give the cow-pox virus to people with small-pox! Thus, the word for cow turned into the word for vaccine!

We can see the v‑c root clearly in both.