A word appearing as ᴱQ. aldeon (aldeond-) “avenue of trees” in the Qenya Lexicon of the 1910s based on ᴱQ. alda “tree” (QL/29). In the contemporaneous Poetic and Mythological Words of Eldarissa it was simply glossed “avenue”.

Neo-Quenya: Since alda “tree” remains in Quenya, I would retain ᴺQ. aldeon(d-) “avenue” for purposes of Neo-Quenya, perhaps with the second element being yondë “region”. Its original sense might have been “region of bordered by trees”, reused to describe a road lined with trees and from there becoming “avenue”.