Where does “bon ghiornu” come from?

bon ghiornu (Sicilian) comes from Sicilian ghiornu, from Sicilian jornu, from Latin diurnum, from Latin diurnus, from Latin diēs, from Proto-Italic djēm, from Proto-Italic *djous, from Proto-Indo-European dyḗws — to be bright; sky, heaven.

Ancestry of “bon ghiornu”, step by step

bon ghiornu traces back through two separate lines of ancestry.

via Sicilian ghiornu

StepLanguageWordMeaning
1SicilianghiornuAlternative form of jornu, especially when...
2Sicilianjornuday
3Latindiurnummasculine accusative singular of diurnus; neuter...
4Latindiurnusof the day; daily; day
5LatindiēsA day, particularly
6Proto-Italicdjēmaccusative singular of *djous
7Proto-Italic*djous
8Proto-Indo-Europeandyḗwssky, heaven; sky god
9Proto-Indo-Europeandyéwssky, heaven
10Proto-Indo-Europeandyew-to be bright; sky, heaven

via Sicilian bon

StepLanguageWordMeaning
1Sicilianbongood
Every word from Proto-Indo-European dyew-Every word from Proto-Indo-European dyéwsEvery word from Proto-Indo-European dyḗws