Where does “シヤーム” come from?

シヤーム (Japanese) comes from Arabic صيام, from Arabic صَامَ, from Arabic و, from Persian یا, from Arabic يَا — {{m|en|O|id=vocative}}.

Ancestry of “シヤーム”, step by step

Step	Language	Word	Meaning
1	Arabic	صيام	verbal noun of صَامَ
2	Arabic	صَامَ	to abstain
3	Arabic	و	and, "comma", "semi-colon"; a divider of words or...
4	Persian	یا	API •; or; either
5	Arabic	يَا	{{m\|en\|O\|id=vocative}}