🔼The name Ar in the Bible
The name Ar (or more complete: ער־מואב; Ar of Moab — see Numbers 21:28) was a city on the southern shore of the river Arnon (Numbers 21:15). When YHWH delivers His famous "do not harass Moab" sermon, He declares that He gave Ar to the sons of Lot (which would be the Ammonites and the Moabites — Deuteronomy 2:9). Much later, the prophet Isaiah declares his blood curdling prophecies against Moab, and foretells its utter destruction, along with Kir of Moab (Isaiah 15:1).
🔼Etymology of the name Ar
The name Ar probably comes from the word עיר ('ir) meaning city:
For a meaning of the name Ar, both NOBSE Study Bible Name List and Jones' Dictionary of Old Testament Proper Names read City.
BDB Theological Dictionary offers: "usually interpreted as capital city (ער = עיר)"