The Spanish word "pato" (meaning "duck") has an interesting journey through Middle Eastern languages. It originated from the Persian word "bat" meaning "duck", which was borrowed into Classical Arabic as "baṭṭ". This word then evolved in Andalusi Arabic (the variety of Arabic spoken in medieval Islamic Spain) as "páṭṭ". Finally, it entered Spanish as "pato", maintaining its meaning of "duck" throughout its journey. This is one of many Spanish words that shows the influence of Arabic and Persian on Spanish vocabulary during the centuries of Islamic presence in the Iberian Peninsula.

Unlike some Spanish words, "pato" doesn't have many etymologically related simpler Spanish words, as it entered Spanish as a relatively standalone term from Arabic. However, you might encounter related words like "patito" (little duck) or "patada" (kick, possibly from the way ducks waddle), though these are derivatives rather than etymologically related words.

There aren't any common English words that are etymologically related to "pato", as English and Spanish acquired their words for "duck" from different sources. English "duck" comes from Germanic origins, while Spanish "pato" comes from Persian via Arabic. This is a good example of how different languages can use completely different word roots to describe the same concept.