Where does “Rúðuborg” come from?

Rúðuborg (Icelandic) comes from Icelandic Rúða, from Danish rude, from Old Norse rúta, from Middle Low German rūde, from Latin rūta, from Ancient Greek ῥυτή — rue.

Ancestry of “Rúðuborg”, step by step

Rúðuborg traces back through two separate lines of ancestry.

via Icelandic Rúða

Step	Language	Word	Meaning
1	Icelandic	Rúða	Rouen
2	Danish	rude	pane; window; square
3	Old Norse	rúta	—
4	Middle Low German	rūde	—
5	Latin	rūta	rue bitter herb
6	Ancient Greek	ῥυτή	rue

via Icelandic borg

Step	Language	Word	Meaning
1	Icelandic	borg	city; castle; a rocky hill
2	Old Norse	borg	A city, town; A castle; Any fortified place
3	Proto-Germanic	burgz	fortification, stronghold; city
4	Proto-Indo-European	bʰr̥ǵʰ-	—

Every word from Ancient Greek ῥυτή →Every word from Latin rūta →Every word from Middle Low German rūde →