Where does “*sorba” come from?

*sorba (Vulgar Latin) comes from Latin sorbum, from Latin sorbus, from Indo-European *ser-.

Ancestry of “*sorba”, step by step

Step	Language	Word	Meaning
1	Latin	sorbum	sorb, fruit of the service tree
2	Latin	sorbus	sorb; service tree; "Sorbus domestica"
3	Indo-European	*ser-	—