nigoþa [OE]
ninthe [MI]
ninth [ME]
nynþ
https://www.etymonline.com/word/ninth#etymonline_v_40498
https://www.merriam-webster.com/dictionary/ninth
https://quod.lib.umich.edu/m/middle-english-dictionary/dictionary/MED29552
https://bosworthtoller.com/23713