Green’s Dictionary of Slang

boondocks n.

[Tagalog bundock, a mountain; orig. used by US milit. (esp. US Marine Corps) to mean the field, the bush, the jungle, anywhere the troops operate that is not designated a firebase, a basecamp or occupied by civilians]

[1940s+] (US) rough country, jungle, an isolated or wild region; plus fig. use as an isolated unappealing place; thus boondocker, one who comes from such a place.