• proficient (Merriam Webster)
• cumulus (Dictionary.com … maybe)
• insuavity (Worthless Word for the Day)

… on the Latin side:

https://twitter.com/#!/latinwordaday/status/204712887435014144
https://twitter.com/#!/LewisandShort/status/204589638118158336

… and the Greek:

https://twitter.com/#!/LiddellandScott/status/204588826314817536