[atchoo]

I was curious about "thesaurus" given that is not a dictionary but still a "word book".

According to Google Translate, apparently Wörterbuch also means thesaurus so OP is correct, it is more ambiguous than dictionary.

The first suggested translation for thesaurus is... thesaurus... so much for compound words eh?

[lifthrasiir]

I specifically said "lexicalized" because the word "wordbook" would be somehow related to "word" and "book" but can mean something else so these words can't no longer stand as a standalone word. Whether the word "thesaurus" can be said to be a "word book" or not is pretty much irrelevant here. If a "wordbook" meant a thesaurus then a plain dictionary would naturally use a different word (or phrase) to avoid confusion. Or more likely, "thesaurus" may not exist as a single word but would be just called a synonym dictionary.

[mgaunard]

A thesaurus is a type of dictionary.

[oefnak]

Synoniemenbüch, probably?

[biztos]

Synonymwörterbuch, apparently:

https://shop.duden.de/collections/worterbucher-und-sprache/p...

[hoseja]

Synonym, of course, being latin.

[oblio]

Lazy just like us. Thesaurus in Romanian is "dicționar de sinonime". I won't bother translating it back to English, you can figure it out :-D

[NoGravitas]

Likewordbook, surely.