Boyd’s Bible Dictionary:

(red). Called also Idumea and Mount Seir. Name given to Esau, his country and people (Gen. 32:3-19; 33:1-16). It lay to the south of Palestine and Moab.

Concise Bible Dictionary:

Name given to Esau because he craved the red pottage of Jacob, Edom signifying red (Gen. 25:30; Gen. 36:1,8,19); but the name is more usually given to his tribe and the territory they possessed. This extended from the land of Moab, southward to the Gulf of Akaba, in length about 100 miles, from about 29° 30' to 31° N, and about 35° 30' E. It is a remarkably mountainous district with lofty peaks and deep glens, but also with very productive plains. It had been called mount Seir (Gen. 36:8). Some of the rocks were so precipitous that Amaziah killed 10,000 of the children of Seir (Edomites) by casting them down from the rocks, whereby they were dashed to pieces (2 Chron. 25:11). Bozrah and Sela, or Selah, were its chief cities.
When Israel was approaching the land of Palestine, Moses appealed to Edom to let them pass through their country, but they refused. The Israelites therefore returned south by way of the Red Sea (Gulf of Akaba) in order to compass the land of Edom, and then kept to the east of Edom until they reached the land of Moab (Num. 21:4).
Edom is constantly referred to in the prophets as having had relations with Israel, and is judged because of its perpetual hatred against them (Ezek. 35:5). God at one time stirred up the king of Edom to punish Israel (1 Kings 11:14), and then again strengthened Israel to punish Edom (2 Chron. 25:10-11). Some of the prophecies however extend to the future. Edom took pleasure in the punishment of Judah when judgment was falling upon it. Of Jerusalem they said, “Rase it, rase it, even to the foundation thereof” Psalm 137:7, evincing, as also do other passages, the hatred and jealousy of the descendants of Esau.
Many prophecies speak of its punishment. When the king of the north in a future day invades Palestine and overthrows countries as far as Egypt, “Edom, and Moab, and the chief of the children of Ammon” will escape, being reserved to be subdued by Israel (Dan. 11:41; Isa. 11:13-14; Obad. 18-19). It is from “Edom” that the Lord Jesus is represented as coming “with dyed garments” because of His having executed judgments (Isa. 63:1). Its destruction will be complete (Obad. 10).
During the captivity the Edomites extended their dominion in the West and possessed Hebron; and some 300 years B.C. the Nabatheans took Petra (which is supposed to be the same as Sela), and established themselves in the district. They settled down and engaged in commerce, and formed the kingdom called by Roman writers Arabia Petraea. Under the Maccabees the Edomites in the west were conquered, and Hebron was recovered. After possession by the Romans, under the withering influence of Mahometan rule the district came to ruin.
The Greek form of Edom is IDUMEA, which occurs only in Isaiah 34:5-6; Ezekiel 35:15; Ezekiel 36:5 and Mark 3:8.

Jackson’s Dictionary of Scripture Proper Names: