Brown Driver Briggs

 Seir = "hairy" or "shaggy"
n pr m
1. patriarch of the Horites, the inhabitants of Edom before the
descendants of Esau, the Edomites
n pr terr
2. the land of Edom, south of the Dead Sea
n pr mont
3. a mountain range in Edom extending from the Dead Sea to the
Elanitic Gulf
  1) apparently also called 'Mount Seir' and extending most of the
distance of the mountain range itself
4. a mountain in northern Judah lying westward from Kirjath-jearim