From the Latin fundus (“bottom”), we get the Spanish fondo (“background”) and hondo (“deep”) — as well as the English profound. After all, when someone says something profound, well, that’s deep.

The mapping of the Spanish f‑n-d (or h‑n-d) to the English (pro)-f-n‑d is straightforward. However, it’s curious that, in hondo, the initial F transformed from Latin into Spanish to an initial H. This is a common pattern, unique to Spanish, that we see in many Latin words as they transformed into Spanish, such as hijo and filial, refuse and rehusar, and higado and fig.