Moseroth
Moseroth (and the singular form Moserah) names a stage in Israel's wilderness journey. The two namings sit in different genres — the bare itinerary list of Numbers 33 and the retrospective notice of Deuteronomy 10 — and the latter adds the detail that Aaron died there.
A Stage in the Wilderness Itinerary
In the marching-list, Moseroth lies between Hashmonah and Bene-jaakan: "And they journeyed from Hashmonah, and encamped in Moseroth. And they journeyed from Moseroth, and encamped in Bene-jaakan" (Num 33:30-31). The notice is bare; the place's only contribution to the list is its sequence between the two adjacent camps.
Aaron's Death at Moserah
Deuteronomy 10 supplies what the Numbers itinerary does not: at Moserah (the singular form of the same name) Aaron dies and Eleazar succeeds him. "And the sons of Israel journeyed from Beeroth Bene-jaakan to Moserah. There Aaron died, and there he was buried; and Eleazar his son served in the priest's office in his stead" (Deut 10:6). The order of camps differs from Numbers — here the journey runs from Beeroth Bene-jaakan to Moserah — but the place itself is the same, and the priestly succession is fixed at this site.