🔼The name Edom in the Bible
Edom bordered Israel on the south and was a kingdom long before Israel (Genesis 36:31). Edom and Israel skirmished throughout their existence. King Saul battled them (1 Samuel 14:47) but David conquered them (2 Samuel 8:14) and Edom remained under Israel's control until the reign of Jehoram (2 Kings 8:20).
The ethnonym אדמי, Edomite, occurs only sporadically in the Bible (Deuteronomy 23:8, 1 Samuel 21:8, 1 Kings 11:14), and is spelled without the signature letter waw. That means that Edomite is spelled the same as Adamite (one of Adam).
In Greek times Edom became Idumea (spelled Ιδουμαια and mentioned only in Mark 3:8) and the roles ironically reversed, since the Herod family was Idumean.
🔼Etymology of the name Edom
In the famous soup-scene where Esau receives his nickname Edom, the author seems to engage in word play. The word for soup (נזיד, nazid) comes from the verb זיד / זוד (zid/ zud), meaning to 'boil' in the literal sense, but figuratively to act proudly or presumptuously. This verb is used in the sense of boiling only once, in our soup-scene. All other occurrences of this verb have to do with arrogance or otherwise aggressive attitudes. It stands to reason that a Hebrew audience understood the aggression to be the literal meaning of this verb, and the meaning of to boil the figurative charge.
When Esau walks in, tired from the field, he demands that Jacob gives him of 'that red stuff, that red stuff.' The word for 'red stuff' is אדם (adom); a word highly similar to the name Edom. The identical root אדם ('dm) is the source for the name Adam. Another derivation is אדמה (adama), meaning field. Esau is a 'man of the field' and even though the word adama is not used but rather שדה (sadeh), also meaning field, the association is clear:
Jacob gives Esau of the red stuff and wings him out of his birth-right. At least, that what he hopes. But just to be sure, he tries to deceive his blind father by dressing up as Esau. Not very clever, especially since the bigger blessing was his already, and Isaac bestowed it on Jacob out of faith, and not because he was tricked (Hebrews 11:20).
The name Edom means Red or Ruddy.