The Spanish word 'nilo' (meaning 'the Nile River') comes from the Latin word 'Nilus', which in turn was borrowed from Ancient Greek 'Νειλος' (Neilos). This is a straightforward borrowing of the proper name for one of the world's most famous rivers, maintaining its meaning and only adapting its form to fit each language's spelling conventions as it passed from Greek to Latin to Spanish.

Since 'nilo' is the proper name for the Nile River, there aren't many common Spanish words directly related to it etymologically. However, you might encounter related adjectives like 'nilótico' (meaning 'Nilotic' or 'relating to the Nile') in geographical or historical contexts.

In English, we can find related words like 'Nile' (the river itself) and 'Nilotic' (relating to the Nile), which share the same Greek origin. The English word 'Nile' also comes from Latin 'Nilus', making it a direct cognate of the Spanish 'nilo'.