ĝangalo

Ĝangalo is one of the small number of Esperanto roots that came from South Asia, and it arrived by the usual colonial route: Sanskrit to Hindi to English to everybody else. What makes it worth a paragraph is that the meaning turned completely over on the journey. Sanskrit jangala described dry, thinly wooded waste ground - the sort of place nothing much grows. English took it for the opposite, the impenetrable green tangle of the tropics, and it is the English sense that every other language, Esperanto included, now carries.

Keep it apart from arbaro, which is the general word for a wood or forest and is itself a build: arbo plus the -ar- suffix for a collection of things, so literally a set of trees. Ĝangalo is not built from anything; the root is ĝangal- entire.

Spelling first, because it is the thing that trips people up. Ĝ is the hatted letter with the sound of English j in jungle, which is exactly the sound you want here, and in the x-system the word is written gxangalo. The adjective is ĝangala, and the figurative sense works as it does in English: a city, an office or a legal system can all be a ĝangalo.