AR (Heb. ‘ār). A city or district of Moab, referred to in a song quoted in Num.21.15, named in Deut.2.9, Deut.2.18, Deut.2.29 and in a prophecy of Isaiah (Isa.15.1).
Ar does have the same radical letters as the common Heb. word for city. The suggestion that Ar was the capital city of the Moabites is worth noting.
Numbers 21:15 and Deuteronomy 2:9 and 28 all use Ar in parallel with Moab itself, thus presenting the possibility that this was another term for an area of Moab. The modern site of el-Misna is a plausible suggestion for Ar’s location.