🔼The name Hor-haggidgad in the Bible
The name Hor-haggidgad occurs in only one scene in the Bible. Numbers 33:32-33 lists Hor-haggidgad as one of the stadia of Israel in the wilderness, in between Bene-jaakan and Jotbathah. Deuteronomy 10:6-7 tells of the same journey, albeit with a bit more detail, and Hor-haggidgad is called Gudgodah (גדגדה).
🔼Etymology of the name Hor-haggidgad
The name Hor-haggidgad consists of three elements. The first part comes from the root group חרר:
The first letter of the last part of our name is ה (he), which is either the definite article (meaning the) or it indicates a motion towards whatever follows.
The final part of our name is the mysterious word גדגד, which is mysterious because we don't know what it means (or even where it came from; "mng. dub". growls BDB Theological Dictionary). Even the authors of the Septuagint didn't know what to do with it, and transliterated this whole name as Mount Of Gadgad (which leads some to suspect that these noble scholars mistook the word חר for הר (har), meaning mountain. The noun חר (hor), with which our name starts never means mountain and should in this context probably be translated with cave or cavern.
NOBSE Study Bible Name List reads a corrected Cavern Of Gidgad but doesn't explain who or what Gidgad might be. Alfred Jones (Dictionary of Old Testament Proper Names) initially copies the Septuagint, but also refers to Gesenius' find of an Ethiopic word guadguada, meaning to beat or to thunder. Hence, says Jones, some onomastics read Cavern Of Thunder.
A Hebrew audience however (and especially those who didn't speak Ethiopic) would probably have figured that the word גדגד and its feminine equivalent גדגדה (hence the name Gudgodah) comes from a diminishing repetition of the word גד (gad), from the verb גדד (gadad), meaning to cut or invade:
Perhaps the name Hor-haggidgad originally meant Cavern Of Thunder in words that once existed in Hebrew but never made it into the narrative of the Bible, and are extant only in Ethiopian scriptures. Perhaps it meant Cavern Of Gidgad and Gidgad was the name of some local deity whose name was imported from some far away land (or, say, of an Ethiopian expat who made that cave his home). But a Hebrew audience would probably have figured this name to mean Cave Of Scrapes (if it was particularly rugged within) or Cavern Of Felicity (if finding this place somehow rendered the Israelites a sense of fortuity, say because it rained).