The Spanish word 'pareo' comes from the Tahitian word 'pāreu', which refers to a traditional wraparound garment. The word entered Spanish through English 'pareu', maintaining its meaning as a lightweight fabric wrap or sarong-like garment commonly worn as beachwear. This is one of the relatively few Spanish words that has Polynesian origins, reflecting the cultural exchange between Pacific islanders and European travelers.

There aren't any simpler or more common Spanish words that are etymologically related to 'pareo', as it's a direct borrowing from Polynesian languages through English.

The English word 'pareu' is directly related to the Spanish 'pareo', as both come from the same Tahitian source word 'pāreu'. In English, 'pareu' is sometimes also spelled as 'pareo' and refers to the same type of garment - a wraparound skirt or dress typical of Pacific Island cultures and now popular as beachwear worldwide.