jungle

English borrowed "jungle" from Hindustani jaṅgal, which came from Sanskrit jaṅgala, meaning an arid or sterile region — a desert, not a forest. The Sanskrit word itself traces back to a substrate language whose identity isn't known. It first shows up in English around 1776, in a translation by Nathaniel Halhed.

The word crossed from Sanskrit's dry, barren wasteland into Hindustani, and by the time English borrowed it, it had come to describe overgrown, uncultivated land — the sense of dense wilderness that stuck.

The facts here don't point to any English cognate; "jungle" stands as a direct borrowing without a known relative in the language.