The Spanish word 'pichi' comes directly from the Mapuche (Mapudungun) language, where 'pichi' means 'small'. This is one of several words that Spanish has borrowed from indigenous languages of South America, particularly in Chile and Argentina where the Mapuche people have historically lived. The word maintains the same meaning and form in both languages.

While 'pichi' itself is a relatively simple word, it's worth noting that in Chilean Spanish, it's often used in compounds and diminutives. However, there aren't any simpler or more common Spanish words that share its Mapuche etymology.

There are no etymologically related English words to 'pichi' since it comes from the Mapuche language, which is indigenous to South America and has not influenced English vocabulary. English speakers might find it helpful to simply remember it as a loanword meaning 'small' in Chilean Spanish.