The Spanish word 'quirquincho', meaning 'armadillo', comes directly from the Quechua word 'khirkinchu', which also meant 'armadillo'. This is one of many words that Spanish borrowed from indigenous South American languages after the Spanish conquest of the Americas. The pronunciation and spelling were slightly adapted to fit Spanish phonological patterns, with the Quechua 'kh' becoming 'qu' in Spanish.

Since 'quirquincho' comes from Quechua rather than Latin or Greek roots, there aren't any simpler or more common Spanish words that share its etymology. This is typical of words borrowed from indigenous American languages, which form their own distinct word families in Spanish.

There aren't any etymologically related English words to 'quirquincho', as it comes from Quechua, an indigenous South American language family that had no contact with English or other European languages until after the Spanish conquest. In English, we simply use the word 'armadillo', which comes from Spanish but from a different root (it literally means 'little armed one' due to the animal's armor-like shell).