Does a Pali thesaurus exist?

When seeking to refine my mental maps of the world in any domain of expertise to more precisely differentiate between similar terms, I have found a thesaurus to be an invaluable tool. The domain of expertise of the Buddha, namely the path from suffering to the end of suffering, is arguably of more importance than any other domain of expertise, and yet, I am not able to find a Pali thesaurus. Does this exist? Is anyone working on this?