The Spanish word 'zanahoria' (meaning 'carrot') has an interesting journey through multiple languages. It originated from the Ancient Greek term 'staphyline agria' (σταφυλίνη ἀγρία), which meant 'wild carrot'. This Greek term was adapted into Hispano-Arabic as 'safunnárya', maintaining its meaning of 'carrot'. As the word made its way into Old Spanish, it became 'çahanoria', and finally evolved into the modern Spanish 'zanahoria'. The transformation from the Hispano-Arabic to Spanish forms shows how the word was adapted to fit Spanish pronunciation patterns, with the 's' sound shifting to 'z' and the double 'n' simplifying to a single 'n'.

There aren't any simpler or more common Spanish words that are etymologically related to 'zanahoria', as it stands quite unique in Spanish vocabulary. The word has maintained its specific meaning of 'carrot' throughout its evolution in Spanish.

While English 'carrot' and Spanish 'zanahoria' both refer to the same vegetable, they are not etymologically related. The Spanish word comes from Greek via Arabic, while the English word 'carrot' comes from a different etymology (from Greek 'karoton'). This is a good example of how different languages can develop entirely different words for the same object through different historical paths.