Carlos Ferrero Martín, in Las palabras son pistolas cargadas, deals in some depth (in Spanish) with the Grandiloquent Dictionary:
bq. This is the result of an ongoing project to collect and distribute the most obscure and rare words in the English language. It also contains a few words which do not have equivalent words in English. At present, the dictionary contains approximately 2300 words, though it is constantly growing.
The dictionary can be consulted online or the current version downloaded as a PDF file (including, oddly, 100 words not included in the online dictionary).
Martín points out that most of the words are of Greek or Latin origin. He points out that junta is not uncommon. I noticed scatology and schwa at a quick glance. Should be taken with a large pinch of salt.