At the beginning of the novel there are four pages of maps showing virtually the entire world and thus the places Jack Shaftoe visits on his long sea voyage late in the 17th century. During stops along the way in places like Egypt, India, Japan and Mexico, we get a sampling of words and phrases in the languages spoken there. Yet even the English words Stephenson throws about demand a glossary, which the author does not provide. Here is a sampling of what you are up against when you tackle this book.
chainshot - Often one can deduce from context what a word means, and that is the case here: "...like chainshot launched from a cannon." The word refers to small cannon balls chained together. This was at one time useful for destroying the masts of enemy ships.
insomniacal - Most of us know the word insomnia, but insomniacal? That was new to me. The story refers to "insomniacal horses and camels." According to the web, this is a word of recent origin, certainly not in use in the 17th century. It refers to someone who seems never to sleep.
obnubilated - This means obscured or covered by a cloud. Again the context helps: "Cherbourg's shore-batteries obnubilated by powder-smoke." Later there is mention of stars "frequently obnubilated by weather."
poniard - The context didn't help me here: "I seem to have lost my poniard -- have you seen it?" It is a small, thin dagger.
steganography - Once again the context helps: "...used some form of steganography in their letters." This is the practice of concealing one message within another. It is different from a coded message, which cannot be read without the code. With steganography, you can read a message, but not the message.
The speller on my computer questions each of these words, which suggests that I am not alone in not being familiar with them. I'll bet William F. Buckley Jr. was, however, with the possible exception of insomniacal.