The Spanish word 'erizo' (meaning 'hedgehog') comes from the Latin word 'ericius', which also meant 'hedgehog' or 'bristled'. This Latin term evolved from an even more primitive Latin root 'er' that referred to hedgehogs. The word has maintained its meaning remarkably well throughout its evolution from Latin to modern Spanish, consistently referring to the spiny little mammal we know as a hedgehog.

The word 'erizo' also appears in the compound term 'erizo de mar' (meaning 'sea urchin'), where the spiny appearance of the sea creature reminded Spanish speakers of the land-dwelling hedgehog. This shows how the spiny characteristic of the original meaning has been extended to describe other similar-looking creatures.

While English 'hedgehog' isn't directly related to 'erizo', the scientific name for hedgehogs, 'Erinaceus', comes from the same Latin root. This can be seen in scientific terms like 'erinaceous', meaning 'of or relating to hedgehogs' or 'hedgehog-like'. Though these words aren't common in everyday English, they maintain the connection to the ancient Latin term for these spiny creatures.