twelfta [OE]
twelfte [MI]
twelfth [ME]
tɯelþ
https://www.etymonline.com/word/twelfth#etymonline_v_24851
https://www.merriam-webster.com/dictionary/twelfth
https://quod.lib.umich.edu/m/middle-english-dictionary/dictionary/MED47457
https://bosworthtoller.com/31202