þreoteoða, þriteogeða [OE]
thritenth [MI]
thirteenth [ME]
þertínþ
https://www.etymonline.com/word/thirteenth#etymonline_v_48737
https://www.merriam-webster.com/dictionary/thirteenth
https://quod.lib.umich.edu/m/middle-english-dictionary/dictionary/MED45532
https://bosworthtoller.com/32038