I'm currently reading through all of Rex Stout's Nero Wolfe mysteries, and one fun feature is that he almost always includes one or more very obscure words. It's a nice little thing to look out for.

In the one I'm currently reading it's, "peculate," meaning to embezzle or steal money. Others include:

• Plerophory - Fullness, especially of conviction or persuasion
• Apodictically - From apodictic: clearly established or beyond dispute
• Usufruct - The right to enjoy the use and advantages of another's property short of the destruction or waste of its substance
• Acarpous - Not producing fruit; sterile; barren
• Yclept - By the name of
• Eruction - A belch or burp

I had a look to see if I could find a full list but sadly not. However most Wikipedia entries for the individual novels include a section called, "The unfamiliar word," if you want to find more.