nigonteoþa [OE]
nintenthe [MI]
nineteenth [ME]
nyntínþ
https://www.etymonline.com/word/nineteenth#etymonline_v_45314
https://www.merriam-webster.com/dictionary/nineteenth
https://quod.lib.umich.edu/m/middle-english-dictionary/dictionary/MED29551
https://bosworthtoller.com/23708