chrestomathy (Dictionary.com)
insuavity (Worthless Word for the Day)
… and from the Latin twitterverse:
https://twitter.com/#!/latinlanguage/status/205090416356368385
https://twitter.com/#!/LewisandShort/status/205043347960770561
… and Greek:
https://twitter.com/#!/LiddellandScott/status/205042700599296000
… not sure if I have some duplicates there …