Feliz (Spanish for “happiness”) comes from the Latin felix, meaning both “happy” and “fertile”.

It is indeed curious how, linguistically, happiness and having children and plentiful crops are deeply intertwined.

From the same root, we get the English felicity, which we can see in the f‑l-z to f‑l-c mapping very clearly.

Most distantly, we also have the English fecund and fetus.