Tesoro Mio

While tutoring the other day, I was helping my student correct a paper he'd written in English for a conference. He had used a word that wasn't quite correct, and I was thinking of synonyms that would be easier for an Italian to pronounce than "thwart." I clicked over to thesaurus.com and searched for thwart.

Tutee: What's that site?
Me: It's an online thesaurus.
Tutee: What's a thesaurus?
Me: It's a book that tells you all the synonyms and sometimes the antonyms for a word. This is just an online version.
Tutee: Woooow, that's amazing! What's it called again?
Me: A thesaurus. Italian has the same word - tesoro - although I guess it means something else, yeah?
Tutee: Yeah, we don't have a thesaurus in Italian. This is great!

I found this hard to believe and asked the first foreigner I could find, which happened to be Erik, whether other languages had thesauri. He said he'd never seen a Swedish thesaurus, although he thinks that one exists.

So those of you who know or have studied another language... have you ever seen a thesaurus in that language? Is it just that English is such a huge language, with words drawn from German, French, Latin, and Greek, that it is inevitable that multiple synonyms exist for every word?