Aranrúth

noun. royal anger

aran (“king”) + rûth (“anger”) The archaic origin of the name can probably explain why assimilation nr > dhr doesn't take place.

aranrúth

proper name. King’s Ire

The name of Thingol’s sword (S/201), translated by Christopher Tolkien as “King’s Ire” (SI/Aranrúth), a combination aran “king” and rûth “anger, wrath” (SA/ar(a), rûth).

Elements

Word	Gloss
aran	“king, lord, chief, (lit.) high or noble person, king, lord, chief, (lit.) high or noble person; [N.] lord (of a specific region)”
rûth	“wrath, anger”