[MrJohz]

But the key point here is that "fire stuff" is still a pretty ambiguous term. Sure, it does describe a lighter, but it also describes lots of other things pretty well. The compound parts give some clues as to the nature of the object in question (a Feuerzeug does have something to do with fire), but fundamentally you still need to know what the word means.

So I don't think compound words magically remove ambiguity, at least not in the general case. Any given compound word could have multiple different meanings, and any given meaning can be described by several compound words.

[MrsPeaches]

As far as I understand it, Zeug means thing in this context.

Stuff is “Stoff” as in Brennstoff.

Fire-thing and burning-stuff.

Lighter is “Zünder“ in German.

Feuerzeug vs Zünder

To close to call regarding which is clearer.

[wirrbel]

Feuerzeug is a lighter, its a fixed term, nothing "wobbly" that relates to fire-stuff.

Zünder is an igniter/detonator, Zündung is the ignition.

Zeug can be used as "thing", but it is frequently used when refearing to gear. So "Feuerzeug" is like "Firegear", "Werkzeug" is the "gear for working" (tools).

[biztos]

There is Zündholz for “match” but lo[0], apparently there is/was Zündzeug:

https://www.dwds.de/wb/dwb/zündzeug

[0]: https://en.wiktionary.org/wiki/lo