Your word should start with the last letter of the word above, and have some sort of connection to each other
So, after Root you could post Topophilia ( is a strong sense of place, which often becomes mixed with the sense of cultural identity among certain peoples and a love of certain aspects of such a place. ) and then Absorption would work.
Ah sorry, I somehow missed the part about the word having to start with the last letter of the past word - I was just going for words with some kind of connection. Thanks for correcting me without being an ass about it
In that case I'm simply going to play the word "Tree" in response to the word "Root"