dun, dune, ofdune [OE]
doun [MI]
down [ME]
daon
https://www.etymonline.com/word/down#etymonline_v_13990
https://www.etymonline.com/word/down#etymonline_v_13992
https://www.merriam-webster.com/dictionary/down#dictionary-entry-2
https://quod.lib.umich.edu/m/middle-english-dictionary/dictionary/MED12470
https://bosworthtoller.com/23993
https://bosworthtoller.com/43070
https://bosworthtoller.com/8106