What is the origin of the word 'yule', as in yuletide?

yule

Old English geol, geola "Christmas Day, Christmastide," which is cognate with Old Norse jol (plural), the name of a heathen feast, later taken over by Christianity; the Germanic word is of unknown origin. The Old English (Anglian) cognate giuli was the Anglo-Saxons' name for a two-month midwinter season corresponding to Roman December and January, a time of important feasts but not itself a festival.

After conversion to Christianity the word narrowed to mean "the 12-day feast of the Nativity" (which began Dec. 25), but was replaced by Christmas by 11c., except in the northeast (areas of Danish settlement), where it remained the usual word.

Revived 19c. by writers to mean "the Christmas of 'Merrie England.' " First direct reference to the Yule log is 17c. According to some sources, Old Norse jol was borrowed into Old French as jolif, hence Modern French joli "pretty, nice," originally "festive"