Kat Icelandic would be norse, old norse the language of the settlers of Iceland who were mainly from Norway. They settled Iceland long after the anglosaxons were celebrating Yule. Christmas in all scandinavian languages is still called Jul, pronounced more or less like "Yule". The midwinter "blot" was the most important in prechristian Scandinavia.

According to my etymological dictionary the word Jul has the followinig etymology:(translating roughly as I write) "In pagan times Jul/jôl was the name of the midwinter feast (blot) held on midwinter eve (januar 12). The word is identical with the anglosaxon geoh(h)ol, géol (english yule). Names of the months were derived from this: gothic "fruma jiuleis", ancient norse "ylir", anglosaxon "se ærra géola" december and "se æfterra géola" january. The germanic roots for the word Yule are *jehwla- and *je(g)wla- which are connected to the latin "jocus" meaning joke, pleasant. If this is the case the word has described a saturnalian feast. French "joli", english "jolly" and italian "giulivo" have the same root"...

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