🔼The name Hadadezer in the Bible
The name Hadadezer belongs to the Aramean king of Zobah, whom David defeated (2 Samuel 8:3). This victory marked a turning point in the economy of Israel. David confiscated gold shields from the servants of Hadadezer (8:7), he levied a colossal amount of bronze from the cities of Hadadezer (8:8), the surviving Arameans became tribute paying servants of David (8:6), and from at least one neighboring kingdom David received congratulatory tributes (namely from king Toi of Hamath; 8:9). Many years later, the wealth of Israel returned to its previous owners, most notably the Aramean king Ben-hadad of Damascus (1 Kings 15:18).
The Chronicler also tells the story of David's victory over Hadadezer, but calls him Hadarezer (הדרעזר 1 Chronicles 18:3 to 19:19), a name which also occurs in 2 Samuel 10:16-19. This discrepancy can be explained in a few ways. Many scholars appear to favor the view that the Chronicler made a text error and mistook the Hebrew letter ד (daleth) for a ר (resh), but this assumption is really fantastically daft. Why would a trained scholar mistake one letter for another one to start with, and why would scores of trained proofreaders and copyists not correct this? And there are two daleths in the name Hadadezer; why would anyone mistake only one for another letter? The names Hadad and Hadadezer were very well known to the Chronicler. Suggesting that the Chronicler consistently mistook a famous name for one that didn't otherwise exist is beyond reasonable defense.
It's much more plausible that both authors wrote what they wrote deliberately. Perhaps the Chronicler altered the name Hadadezer to hide the name Hadad in much the same way as the name Eshbaal was altered into Ish-bosheth. Or perhaps Hadarezer was a personal name and Hadadezer an honorary title (like Abimelech or Caesar). We simply don't know, but it's highly unlikely that all this would be due to a persistent error.
🔼Etymology of the name Hadadezer
The name Hadadezer consists of two elements. The first part is the same as the name Hadad, which belonged to the primary Aramaic deity, which in turn derived from the verb חדה, to thunder or make noise:
The second part of our name comes from the verb עזר (azar), meaning to help or support:
For a meaning of the name Hadadezer, NOBSE Study Bible Name List reads Hadad Is A Help, Jones' Dictionary of Old Testament Proper Names proposes Whose Help Is Hadad and BDB Theological Dictionary has Hadad Is Help(er).